Seminars and Colloquia at ESO Garching and on the campus
December 2015
Abstract
Stellar dynamical modelling is an important tool for uncovering the properties of galaxies and studying their otherwise invisible components, as the Super Massive Black Holes (SMBH) in their cores and dark matter. Nowadays, the vast majority of the available modelling codes assume axial symmetry. However, in observations, it is possible to find signs of non-axisymmetry, as isophotal twists and kinematic misalignment in slowly rotating massive ellipticals. Whenever axisymmetric codes are applied to intrinsically non-axisymmetric systems, they provide uncertain results in terms of the accuracy in SMBH mass estimates, orbital structure and Mass-to-Light ratio. Fabrizio aims at tackling these inconsistencies by developing a new triaxial implementation of the orbit based Schwarzschild's method. After an introduction on the importance of stellar dynamical modelling, Fabrizio will describe the modifications he carried out on the axisymmetric implementation by Thomas J. et at (2004) of the orbit based Schwarzschild's method and present the initial results of his project.
Abstract
Orbiting and landed missions to Mars have revolutionized our understanding of the history and evolution of the terrestrial planets in our Solar System, yet new observations indicate the potential release of biomarker gases and possible unaccounted sub-surface reservoirs of water on Mars. These measurements point to highly dynamic processes that are particularly challenging to detect with current orbiting assets due to restricted spectral resolution and the limited cadence and repeatability of the sampled regions.
Within the next decade, unique space and ground-based assets will become available opening unprecedented windows to explore the atmospheres of Mars and Venus. In particular, upcoming Extremely Large Telescopes will provide unprecedented high-resolution spectroscopy and high spatial resolutions, permitting the study of complex molecules and isotopic ratios at record sensitivities and resolutions.
In this talk, I will present the current frontiers in the exploration of terrestrial planets and how the synergies between future space and ground astronomical assets will transform our understanding of the composition, stability and evolution of the Martian atmosphere.
Abstract
Neutrinos are extremely weakly interacting particles, but have a large impact ondifferent physical processes, like beta decay and big bang nuclear synthesis.The discovery of neutrino oscillations by Super-Kamiokande in 1998 studyingatmospheric neutrinos and by SNO in 2001/2002 studying solar neutrinos led to alarge activity in neutrino physics culminating in this years Nobel prize. Thediscovery implies that neutrinos are massive and lepton flavour is notconserved clearly demonstrating the need for new physics beyond the StandardModel of particle physics. Today we know all three mixing angles in the leptonsector and that at least two neutrinos are massive. However severalquestions are not answered yet: Are neutrinos Dirac or Majorana particles? Whatis the origin of neutrino mass? What is the absolute neutrino mass scale? Whatis the mass ordering of neutrinos? Is there CP violation in the neutrino sector?
In this lecture series Michael will give an introduction to neutrino physics, outline what we currently know and discuss the open questions. The first two lectures (Dec 10+11) will give a broad overview of neutrino physics and the third lecture (Dec 14) will focus more specifically on a way to systematically understandthe generation of neutrino mass. We will discuss the experimental prospects to test neutrino mass generation in different experiments.
Abstract
Neutrinos are extremely weakly interacting particles, but have a large impact ondifferent physical processes, like beta decay and big bang nuclear synthesis.The discovery of neutrino oscillations by Super-Kamiokande in 1998 studyingatmospheric neutrinos and by SNO in 2001/2002 studying solar neutrinos led to alarge activity in neutrino physics culminating in this years Nobel prize. Thediscovery implies that neutrinos are massive and lepton flavour is notconserved clearly demonstrating the need for new physics beyond the StandardModel of particle physics. Today we know all three mixing angles in the leptonsector and that at least two neutrinos are massive. However severalquestions are not answered yet: Are neutrinos Dirac or Majorana particles? Whatis the origin of neutrino mass? What is the absolute neutrino mass scale? Whatis the mass ordering of neutrinos? Is there CP violation in the neutrino sector?
In this lecture series Michael will give an introduction to neutrino physics, outline what we currently know and discuss the open questions. The first two lectures (Dec 10+11) will give a broad overview of neutrino physics and the third lecture (Dec 14) will focus more specifically on a way to systematically understandthe generation of neutrino mass. We will discuss the experimental prospects to test neutrino mass generation in different experiments.
Abstract
Although mergers and starbursts are often invoked in the discussion of quasar activity and its effect on galaxy evolution, several studies have questioned their importance or even their presence in quasar host galaxies. In this talk, I will discuss results from a long campaign of space- and ground-based imaging and spectroscopic observations of z < 0.5 QSO hosts that imply that mergers are indeed essential for the triggering of QSO activity, and that these mergers invariably induce starbursts either during and/or shortly after the merger. In particular, I will discuss observations of a sample of host galaxies previously classified as passively evolving ellipticals. Our results clearly show that these galaxies have undergone major episodes of star formation in the past ~2 Gyr. The morphologies of the host galaxies suggest that these aging starbursts were induced during the early stages of the mergers that resulted in the elliptical-shaped galaxies that we observe today. The current AGN activity likely corresponds to the late episodes of accretion predicted by numerical simulations, which occur near the end of the mergers, whereas earlier episodes may be more difficult to observe due to obscuration. I will discuss numerical simulations that indicate that any potential current star formation or young stellar populations in these hosts would be confined to the central few kiloparsecs, a region that is typically outshined by the bright nucleus. I will also discuss our efforts to search for these starbursts in type-2 QSOs. Finally, I will discuss our ongoing work to probe the co-evolution of black holes and their hosts through scaling relations as a function of time.
Video
Abstract
Semi-annihilation is a generic process in models where dark matter is stabilised by a symmetry larger than Z2, with two initial and an odd number of final dark sector particles. Yi will illustrate how the presence of semi-annihilation affects dark matter phenomenology, including dark matter relic density and indirect detection, in a number of simplified models.
Abstract
Neutrinos are extremely weakly interacting particles, but have a large impact ondifferent physical processes, like beta decay and big bang nuclear synthesis.The discovery of neutrino oscillations by Super-Kamiokande in 1998 studyingatmospheric neutrinos and by SNO in 2001/2002 studying solar neutrinos led to alarge activity in neutrino physics culminating in this years Nobel prize. Thediscovery implies that neutrinos are massive and lepton flavour is notconserved clearly demonstrating the need for new physics beyond the StandardModel of particle physics. Today we know all three mixing angles in the leptonsector and that at least two neutrinos are massive. However severalquestions are not answered yet: Are neutrinos Dirac or Majorana particles? Whatis the origin of neutrino mass? What is the absolute neutrino mass scale? Whatis the mass ordering of neutrinos? Is there CP violation in the neutrino sector?
In this lecture series Michael will give an introduction to neutrino physics, outline what we currently know and discuss the open questions. The first two lectures (Dec 10+11) will give a broad overview of neutrino physics and the third lecture (Dec 14) will focus more specifically on a way to systematically understandthe generation of neutrino mass. We will discuss the experimental prospects to test neutrino mass generation in different experiments.
Abstract
Millimetron is a planned 10-meter class space telescope for the far infrared to millimeter wavelengths (approx. 20 microns to 1 cm). It is designed to study very weak astronomical sources such as high-z galaxies and also to act as an arm of a space-Earth interferometer with the unprecedented angular resolution for studying black holes. In this talk the main features and the current state of development of Millimetron will be summarized and it will be shown what it is expected to contribute to the studies of cosmology and the distant Universe.
Abstract
Observations of the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA) have a large potential for revolutionizing our understanding of our host star with far reaching implications for stars in general. The radiation emitted at ALMA wavelengths originates mostly from the chromosphere – a complex and dynamic layer between the photosphere and the corona, which plays an important role in the transport of energy and matter and thus the heating of the outer layers of the solar atmosphere. Despite decades of intensive research, the chromosphere is still elusive and challenging to observe owing to the complicated formation mechanisms of currently available diagnostics. ALMA will change the scene substantially as it serves as a nearly linear thermometer at high spatial, temporal, and spectral resolution, enabling us to study the complex interaction of magnetic fields and shock waves and yet-to-be-discovered dynamical processes. Furthermore, radio recombination and molecular lines may have great diagnostic potential but need to be investigated first. These unprecedented capabilities promise important new findings for a large range of topics and fundamental questions in contemporary solar physics. As a part of ongoing development studies, an international network has been initiated in 2014, which aims at defining and preparing key solar science with ALMA through simulation studies: SSALMON - Solar Simulations for the Atacama Large Millimeter Observatory Network (http://ssalmon.uio.no). I will give an introduction to solar observations, the anticipated results for ALMA, and activities of SSALMON.
Abstract
The physical nature of the cosmic dark matter remains elusive, but several well-motivated extension of the particle-physics standard model provide candidates that are experimentally searched. The axion, a hypothetical very low-mass boson motivated by quantum chromodynamics (QCD), will be introduced and ongoing experimental searches as well as astrophysical limits will be reviewed. The interest in axion dark matter has recently surged and a number of completely new search initiatives have emerged.
Video
Abstract
We present a new method to constrain the grain size in protoplanetary disks with polarization observations at millimeter wavelengths. If dust grains are grown to the size comparable to the wavelengths, the dust grains are expected to have a large scattering opacity, and thus the continuum emission is expected to be polarized due to self-scattering. We perform 3D radiative transfer calculations to estimate the polarization degree for the protoplanetary disks that have a lopsided surface density distribution observed with a face-on view. We find that the polarization degree is as high as 2.5% with a subarcsec spatial resolution if the grain size is comparable to the observed wavelength. This method opens a new window on grain-size constraint with ALMA.
November 2015
Abstract
I present results from numerical simulations of star cluster formation, and discuss how the physical processes involved in star formation may lead to the observed properties of stellar systems and whether or not these properties may vary in different environments.
Abstract
Large-scale cosmological simulations (such as Illustris and EAGLE) successfully describe the formation of elliptical and spiral galaxies. A challenge for such simulations is, however, to produce "starburst galaxies", which have much larger star formation rates (SFRs) than normal "main sequence" galaxies. With high-resolution zoom simulations with AREPO I will show how the SFR-enhancement during a merger-induced starburst can be significantly increased when increasing the spatial resolution, and this can likely explain the paucity of starbursts in the Illustris simulation. Furthermore, I will present results from a study of bursty star formation cycles in galaxies from the Feedback In Realistic Environments (FIRE) simulations. An interesting consequence of these burst cycles is that they significantly increase the scatter in the "main sequence of star-forming galaxies" for galaxies with stellar masses smaller than ~10^9 solar masses.
Abstract
The chemistry of high-mass star forming regions is usually identified
with the chemistry of hot cores, which are rich in gas-phase complex
organic molecules due to heating by central massive young stellar
objects (MYSOs). The advent of wide-bandwidth systems on (sub)millimeter
interferometers has made it possible to conduct “spectrally blind”
surveys with the spatial resolution to distinguish individual cores
within clustered high mass star forming regions. I will present initial
results from one of the first such large-scale surveys, the
Submillimeter Array (SMA) Survey of Protocluster Evolution. Covering ∼8
GHz of bandwidth in the 1.3 mm window (including lines of CH3CN,
CH3OCHO, H2C2O, and HNCO) at ∼3′′ resolution, the SMA survey reveals a
remarkable chemical and evolutionary diversity, both across the survey
sample (comprised of GLIMPSE Extended Green Objects) and within
individual (proto)clusters. In addition to “classic” hot cores
containing both O- and N-rich organics, we identify populations of
“weak” hot cores, characterized by weak CH3CN emission and a lack of
O-rich complex molecules, and of line-poor cores, characterized by
emission in SO and CO isotopes and a lack of complex molecules. I will
also discuss the most surprising source discovered in the SMA survey:
G11.92−0.61 MM2. The best candidate for a massive pre-stellar core to
date, MM2 is an extreme test case for astrochemical models.
Abstract
Galactic Archaeology is a coined term to describe the fact that the Milky Way's history is encoded both in the amounts of various chemical elements seen in the spectra of stellar atmospheres (abundances), and in stellar motions. One of the pillars of Galactic Archaeology is the use of stellar abundance ratios as an indirect age estimator, which although imprecise, has been proved useful in providing relative ages between the different galactic components. The lack of more precise age determination for large samples of field stars is one of the main reasons why different scenarios for the formation of our Galaxy can still be accommodated to current observational constraints, thus preventing a clear picture of the Milky Way's assembling history. Another difficulty is that most of the available information (especially on ages) has been confined to a region close to the Sun. As it will be shown in this talk, these two main obstacles can now start to be overcome thanks to a) large spectroscopic and photometric surveys covering larger portions of the Milky Way, and b) the combination of the photometric and spectroscopic information with that coming from asteroseismology. The latter promises a breakthrough in the field of Galactic Archaeology, as it brings the opportunity to, for the first time, measure ages for large samples of distant field giant stars, which cover a large age-baseline. When combining this information with that soon available from Gaia, the field of Galactic Archaeology will be shaken and modelers will certainly have less flexibility in finding models that comply to these precious new observational constraints.
Abstract
There have been many attempts to apply the powerful tools of statistical mechanics to self-gravitating N-body systems such as star clusters, galaxies, and planetary systems. Scott will describe why this is difficult, some notable failures and successes, and recent work on two arenas where these tools offer new insight: the distribution of young stars in the central parsec of our Galaxy, and the distribution of orbits of exoplanets.
Abstract
Stars, in the course of their evolution (aging), lose most of their initial mass before they end up as planetary nebulae/white dwarfs (in case of low and intermediate mass) or supernova remnants/neutron stars (in case of high mass stars). Studying cold stellar ejecta is possible mainly in the infrared, a radiation that can be probed most efficiently from Space. In my talk I will review how ground-based facilities and recent Space missions have contributed to our knowledge of late stages of stellar evolution, concentrating on some aspects I was involved in: like so called double- or mixed-chemistry in stellar ejecta, the detection of very large molecules composed of 60 and more carbon atoms (fullerenes), and recognition of unusual yellow hypergiant.
Abstract
After an overview of Ocean Networks Canada’s goals and objectives, comparisons will be made with other large scale research infrastructure at the service of the natural sciences. Approaches, challenges and successes in the areas of engineering will be compared and contrasted. An overview of approaches to management, including overall corporate strategy and sustainability, risk management and mitigation, as well as user access will be covered.
Video
Abstract
Did you see the movie "Interstellar" (2014)? It deals with the future of mankind. The Earth is dying and therefore some teams were sent to search for a habitable planet. The famous relativist Kip Thorne, professor emeritus from CalTech, was executive producer and scientific consultant. Thanks to him and to the director Christopher Nolan as well as his brother Jonathan Nolan who wrote the screenplay, Interstellar is a fascinating, scientifically correct and very stimulating film.
The science-fiction movie deals with interstellar space travel, warping of space and time, time travel, black holes and wormholes. In this talk we will have a close look to the science of Interstellar and ask whether the phenomena shown in the film could really happen in this way in nature – and in our future.
Abstract
The Big Bang nucleosynthesis predicts about three times as much lithium than that remains today in the old main sequence stars. This is the so-called "cosmological lithium problem". In the past astronomers have speculated on what might be responsible for the lithium deficit. Ideas included as yet unknown aspects of particle physics, nuclear physics or even new models of cosmology. My model provides a new solution: the lithium was first destroyed and re-accumulated by these stars shortly after they were born.
Abstract
In this talk, I will present our recent submm observation about lyman alpha blobs (LABs). Using the Herschel PACS and SPIRE data, SCUBA-2 data and ALMA, we study the LABs in J2143-4423 at z=2.38 and SSA22 at z=3.1. Two out of 4 LABs in J2143-4423 and 8 out of 23 LABs are found to be associated with submm sources with high SFRs, suggesting active SF may be the powering source for the extended lyman alpha emission in some LABs. Our preliminary ALMA results among four LABs in SSA22 show that multiple submm counterparts are associated with most of LABs, may suggesting the LABs are the site forming galaxy protoclusters in their early stage.
Abstract
Massive stars are rare and short-lived. Nevertheless, through their extreme
brightness, strong outflows and powerful explosions, they heat and stir
their surroundings, drive outflows on galactic scales, are thought to be
responsible for reionization and the main production the heavy elements in
the Universe. Because of their large impact, evolutionary models of massive
stars are an essential ingredient for a wide variety of astrophysical
problems. Recently it has become clear that the majority of massive stars,
possibly as much as 7 out of 10, will experience severe interaction with a
binary companion. I will discuss several aspects of our quickly increasing
understanding of how this affects (1) the lives of massive stars, (2) our
interpretations of observations of young stellar populations nearby and at
high redshift and transient phenomena and (3) our understanding of the role
that massive stars play through their radiative, mechanical and chemical
feedback.
Video
Abstract
The object formed at the beginning of the star formation process, the first hydrostatic core (FHSC), has been predicted theoretically. Because of its short time scale, deeply embedded nature, and low luminosity, it is not easy to confirm the FHSC observationally. To date, only a handful sources are recognized as the candidates for FHSC. Two sources in the Barnard 1b (B1-b) core are bright in submm/mm wave ranges but dark in mid-IR even in the Spitzer MIPS 24 and 70 micron bands. The physical and chemical properties of these two sources have been studied with the single-dish and interferometer in the wave range from 7 mm to 0.85 mm. The very low dust temperatures of T_dust < 20 K, the low bolometric luminosities of 0.15--0.31 L_sun, the high D/H ratio of ~0.2, and low velocity molecular outflows imply that these two sources in the B1-b core are in an earlier evolutionary stage than most of the known class 0 protostars. Especially, the properties of the northern source, B1-bN, having an internal luminosity of < 0.01--0.03 L_sun, agree with those of the FHSC predicted by the numerical simulations.
Abstract
Accretion is the process by which most objects in the Universe grow in mass: from young stellar objects still in the star-forming process, through accreting white dwarfs and neutron stars, to stellar-mass black holes and supermassive black holes at the centre of galaxies (active galactic nuclei). Although the importance of accretion has been recognised for many years, the detailed physics is still poorly understood. In this talk I will discuss the already known similarities between accreting compact objects, and present new phenomenological spectral/timing similarities observed across all types of accreting systems, compact or not. The most recent results quantitatively link the observed X-ray variability in accreting black holes to the optical variability of accreting white dwarfs and young stellar objects. These results suggest a common physical mechanism driving accretion-induced variability across all mass and size scales, irrespective of the accretor type. I will conclude by discussing some future prospects to this field and posing open questions in the context of further unifying the accretion phenomenology of young stellar objects to those of accreting compact objects.
October 2015
Abstract
The nearly 200000 spectra of z>2 quasars in the Baryon Oscillation Spectroscopic Survey have resulted in measurements of the autocorrelation of the Lyman alpha absorption by the intervening intergalactic medium, and cross-correlations of these absorption with quasars and damped Lyman alpha systems. Results on the measurement of the Baryon Acoustic Oscillation scale at high redshift, the large-scale bias and redshift distortions in the Lyman alpha forest, and the bias factors of quasars and DLAs will be summarized. A new surprising result has been the detection of Lyman alpha emission correlated with high-redshift quasars, using nearly a million spectra of lower redshift galaxies that may contain background emission line galaxies or other diffuse Lyman alpha emission. The detection is still marginal, but if correct it can only be accounted for by known star-forming galaxies if most Lyman alpha photons produced from the stellar ionizing light at z ~ 2.5 manage to escape from low surface brightness halos surrounding star-forming galaxies. Alternatively, some of the diffuse Lyman alpha emission may be due to intergalactic heating associated with quasars.
Abstract
The top quark is the heaviest elementary particle known and its mass is a fundamental parameter of the Standard Model (SM). The value of the top-quark mass affects theory predictions of particle production cross-sections required for exploring Higgs boson properties and searching for New Physics (NP). Its precise determination is essential for testing the overall consistency of the SM, to constrain NP models, through precision electroweak fits, and has an extraordinary impact on the Higgs sector, and on the SM extrapolations to high-energies.
The methodologies, the results, and the main theoretical and experimental challenges related to the top quark measurements and combinations are discussed and reviewed. Finally, the prospects for the improvement of the top-quark mass precision during the upcoming LHC runs are briefly outlined.
Abstract
Using the Herschel Space Observatory we have observed a representative sample of 87 powerful 3CR sources at redshift z<1. The far-infrared (FIR, 70-500 micron) photometry is combined with mid-infrared (MIR) photometry from the Wide-Field Infrared Survey Explorer (WISE) and catalogued data to analyse the complete spectral energy distributions (SEDs) of each object from optical to radio wavelength. To disentangle the contributions of different components, the SEDs are fitted with a set of templates to derive the luminosities of host galaxy starlight, dust torus emission powered by active galactic nuclei (AGN) and cool dust heated by newly formed stars. The level of emission from relativistic jets is also estimated, to determine the maximum thermal contribution of the measured FIR emission.
On the one hand the new data are in line with the orientation-based unification of high-excitation radio-loud AGN, in that the dust torus becomes optically thin longwards of 30 micron. On the other hand, the low excitation radio galaxies and the MIR weak sources are an MIR- and FIR-faint AGN population different from the MIR-bright high-excitation population; it remains an open question whether they are at a later evolutionary state or an intrinsically different population.
The derived luminosities for host and dust heated by star formation are converted to stellar masses and star formation rates (SFR). Compared to other galaxy populations at the same epoch, the host-normalized SFR of the bulk of the 3CR sources lies at a low level. Estimates of the dust mass yield a 1-100 times lower dust/stellar mass ratio than for the Milky Way, indicating that these 3CR hosts have very low levels of interstellar matter explaining the lack of star formation. Less than 10% of the 3CR sources show levels of star formation above those of the main sequence of star forming galaxies.
Abstract
Cluster scientists and students performing research in the Excellence Cluster's Research Area E "What is the nature of dark matter and cosmic acceleration?" come together to present selected topics in scientific talks.
This event is organised by the Research Area E leaders, Jochen Weller (LMU) and Hans Böhringer (MPE), as well as the Excellence Cluster Universe.
Abstract
We use a spherical-symmetric ionospheric reference model plugged into a three-dimensional Particles-In-Cell electromagnetic code [IAPIC] to simulate the Earth magnetosphere-ionosphere coupling. Our aim is to investigate the time-dependent content and dynamics of the 3D magnetosphere in response to thermal ions plasma supply from the ionosphere. Our newly developed 3D PIC model has a finer grid size (0.1-0.2 RE), a H+ to electron mass ratio of up to few hundred, includes Earth gravity and tilt of the dipole field. Most importantly, IAPIC has the capability to consider distinct species with different masses and charges and to follow them in time separately in the simulation box. We present our first results for the content and dynamics of the magnetosphere following H+ and O+ supply from the ionosphere in the conditions of northern IMF of the solar wind.
Abstract
Planets are ubiquitous in our Galaxy, in systems far more diverse than predicted by theoretical models that could reproduce the properties of our own Solar System. I will discuss how scaling laws between the properties of protoplanetary disks and exoplanets and the mass of the central star are key to identifying the physical processes that shape planetary systems. I will also examine the spread in disk properties relevant to planet formation and make a link to the diversity of planetary systems.
Abstract
Prof. Dr. Jacco Vink (Anton Pannekoek Institute, U Amsterdam) who is a Cluster guest will present these lectures at MPE:
Tuesday, 20 October 2015, 11:00-12:30
Part 1: Supernova remnants structure and evolution
Wednesday, 21 October 2015, 11:00-12:30
Part 2: Thermal X-ray emission from supernovae: type Ia vs. core collapse supernova remnants
Thursday, 22 October 2015, 11:00-12:30
Part 3: Cosmic-ray acceleration by supernova remnants
Abstract
Nuclear Star Clusters (NSCs or NCs) can provide a visible record of the gas and star fuelling of galactic nuclei. The fuelling and the formation processes for these nuclei is still not well understood. The associated evolution has so far been studied numerically at resolutions from 100 down to 50 pc. Such resolutions are not high enough to resolve the main nuclear structures, e.g., nuclear disks with scales of 10 to 50 pc. Using simulations of dwarf galaxies at parsec resolution, Nicolas will present an updated view of the formation and evolution of stellar clusters, emphasizing the impact of the stellar feedback and spatial resolution.
Abstract
Prof. Dr. Jacco Vink (Anton Pannekoek Institute, U Amsterdam) who is a Cluster guest will present these lectures at MPE:
Tuesday, 20 October 2015, 11:00-12:30
Part 1: Supernova remnants structure and evolution
Wednesday, 21 October 2015, 11:00-12:30
Part 2: Thermal X-ray emission from supernovae: type Ia vs. core collapse supernova remnants
Thursday, 22 October 2015, 11:00-12:30
Part 3: Cosmic-ray acceleration by supernova remnants
Abstract
The evolution of binary stars may lead to stripping of red giant stars. If this happens on the first giant branch, the remnant is either a helium white dwarf or an subluminous B (sdB) star. The companion may be a main sequence star or another white dwarf. In recent years this evolutionary mosaic has been completed by the discovery of helium-core objects of very low mass (<0.3 Msun), now termed extremely low mass white dwarfs on the one hand and the EL CVn stars on the other. We present results from quantitative spectral analyses of such objects and discuss their relation to the core helium burning siblings, the sdB stars.
Abstract
Prof. Dr. Jacco Vink (Anton Pannekoek Institute, U Amsterdam) who is a Cluster guest will present these lectures at MPE:
Tuesday, 20 October 2015, 11:00-12:30
Part 1: Supernova remnants structure and evolution
Wednesday, 21 October 2015, 11:00-12:30
Part 2: Thermal X-ray emission from supernovae: type Ia vs. core collapse supernova remnants
Thursday, 22 October 2015, 11:00-12:30
Part 3: Cosmic-ray acceleration by supernova remnants
Abstract
I will present ALMA observations of some of the most luminous quasi-stellar objects (QSOs) known, investigating their far-infrared emission and discussing an extremely broad and luminous double-peaked [CII] line in a QSO at redshift z=4.6. The parent sample was compiled from multi-wavelength sky survey data, with which we were able to identify the most luminous (unobscured) QSOs in the Universe. Of over 100,000 broad-line quasars identified in the SDSS, just 90 have bolometric luminosities greater than 10^14 solar luminosities (as or more luminous than the most luminous obscured quasars currently known). We are for the first time determining the far-infrared properties of these most extremely luminous QSOs, and can estimate their contribution to the global star formation rate. Furthermore, the [CII] emission indicates a massive rotating disk around an extremely massive black hole that was already established at high redshift.
Abstract
Very recently, the Nobel Prize in Physics 2015 was awarded for the discovery of neutrino oscillations and the fact that neutrinos have mass. This feature tells us that there is new physics beyond the Standard Model of particle physics. Emiliano will review the mechanism of generation of neutrino masses in simple extensions of the Standard Model. In particular, he will focus on one-loop corrections to the light neutrino mass matrix in the context of low scale type I seesaw scenarios and their implications in experimental searches for neutrinoless double beta decay.
Abstract
Mass accretion onto supermassive black holes occurs on scales beyond the diffraction limit of any single optical/infrared (IR) telescope. Thanks to the resolution power of the VLT Interferometer, we are now tapping into the outer accretion structure of active galactic nuclei (AGN) - commonly referred to as the "dusty torus". Several surprising results are challenging our current paradigm: While the bulk of the mid-IR emission originates from perpendicular where models would put the torus, the IR emission as a whole appears to be made of two components. In this talk I will give a basic introduction to IR interferometry and discuss what our recent results tell us about AGN unification and the physical processes that regulate accretion and feedback. I will also give a brief glimpse into how IR interferometry can help us establishing AGN as cosmological distance measures.
Video
Abstract
The Excellence Cluster Universe organizes the Research Area B Science Day. Experimental as well as theoretical Cluster scientists and students who are active in the field of symmetries in the early Universe come together to present current research results and developments.
Abstract
Understanding the physical processes that drove the reionization of the early Universe is one of the main outstanding issue of cosmology. The common view identifies star-forming galaxies and active galactic nuclei (AGN) as main drivers of cosmic reionization, but little is known about their relative contributions to this process. Forthcoming facilities, such as JWST and the E-ELT, will provide high-quality spectra of thousands of high-redshift galaxies at rest-frame ultraviolet and optical wavelengths out to the epoch of reionization. To prepare for the exploitation of these revolutionary datasets, we have computed a suite of models tailored to the interpretation of the spectral signatures of the first ionizing sources in the early Universe, using dedicated photoionization calculations. In this talk, I will present new photo-ionisation models of nebular emission from star-forming galaxies and AGN and I will show how these model predictions can help us gain new insight into the physical properties of high-redshift galaxies. I will also describe the way in which new ultraviolet and standard optical diagnostics can best help distinguish between spectral features associated with active galactic nuclei, starbursts and shocks in primeval galaxies. To conclude, I will describe how such models can be easily implemented in galaxy spectral analysis tools.
Abstract
During the past decade, the number of known planets has increased explosively, revealing an extreme range in planet compositions. The origin of this diversity is largely unknown. It is also unknown how common access to surface water and organics is on these planets, and thus the frequency of chemically habitable planets. I will present on how these questions can be addressed through a combination of astrophysical observations and laboratory simulations of the chemistry present in protoplanetary disks, the birthplaces of planets. We use spatially and spectrally resolved observations (ALMA and SMA) to explore the organic inventory, isotopic fractionation chemistry, and other chemical structures in disks. In parallel, we use laboratory ice experiment to quantify how these observed gas phase abundances relate to the total volatile reservoirs in disks, which are typically dominated by icy grain mantles. Recent highlights include observations of spectacular chemical ring structures that trace condensation-, temperature- and radiation-regulated chemistry, new constraints on isotopic fractionation during planet formation, and the detection of the first complex molecule in a disk. I will discuss these observations in light of laboratory constraints on ice chemistry, and how they compare with the chemical compositions found at earlier stages of star formation and in the Solar System.
Video
September 2015
Abstract
The global star formation (SF) law — the relation between star-forming gas and SF rate (SFR) — is reexamined in a large sample of 181 local star-forming galaxies with infrared luminosities (SFR) spanning almost five orders of magnitude. The surface density of dense molecular gas (as traced by HCN) has the tightest and linear correlation with that of SFR. The ΣSFR is a steeper function of the total gas Σgas (molecular gas with atomic gas) than that of molecular gas ΣH2. We further show that the SFR and a variety of dense gas tracers (e.g., HCN, CS, their high-J and high-J CO) are all linearly correlated for both the Galactic dense cores in our Milky Way and star-forming galaxies near and far. This has immediate implications on the modes of SF in galaxies because the dense cores are the sites of the active SF, and thus the basic units in contributing to the SF. The SFR should depend linearly upon the mass of dense molecular gas (the SF law!). These ground-based observations of last decade and recent Herschel results highlight what the ALMA can deliver on the studies of "SF laws" across large redshift ranges and on most SF scales.
Abstract
This year, we celebrate the centenary of Einstein's theory of general relativity. When the theory was conceived, the number of experimental tests to confront the theory with was limited. Since then we have come a long way. In particular astronomical observations provide precision tests that were inconceivable even 50 years ago. We use neutron stars observable as pulsars to provide the most precise tests for strongly self-gravitating bodies, to prove that gravitational waves exist or to measure the effects of curvature of space time. We also attempt to determine the properties of black holes, such as their mass and spin to test the description of black holes within general relativity. One of the highlights will be an image of the "Cshadow" of the supermassive black hole in the centre of our Milky Way. Soon we also expect that gravitational wave detectors open up a new window to Einstein's Universe. In all cases, neutron stars or black holes play a crucial role. In this talk I will review some of the current and future tests of general relativity and compare those results with tests of alternative theories.
Abstract
Initial conditions are crucial to understanding the formation of massive stars, which is still a mystery. One of the most debated points is whether massive star formation is a fast or slow process. Tan et al. (2013, ApJ, 779, 96, hereafter T13) discovered two massive starless cores C1-N and C1-S with ALMA. Their study suggests ~mG magnetic field be present if the cores are virialized. Here we present astrochemical study with observation and modeling. We use deuterium fraction Dfrac = [N2D+]/[N2H+] as chemical clock. We utilize the chemical model from Kong et al. (2015, ApJ, 804, 98), and explore the effects of different core collapsing rates relative to free-fall. The chemical network includes spin states, deuterium, and freeze-out. For each collapsing rate, we explore models with different initial density, initial depletion, initial ortho-to-para H2 ratio, and cosmic-ray ionization rate. Then we compare model results with observations collected from ALMA, CARMA, JCMT, IRAM 30m, and NRO 45m telescopes. Multi-transition fitting of N2D+ and N2H+ lines are performed in order to have the most accurate determination of the deuterium fraction so far possible. Comparisons between the observation and model predictions suggests that both C1-N and C1-S have collapsed at a rate at least 10 times slower than free-fall. This supports the dynamical study in T13, and indicates the potentially important role of magnetic fields in slowing down collapse. We will also present initial results from several ALMA Cycle 2 projects that are related to massive starless cores.
Abstract
We propose a simple mechanism for generating ordinary luminous and dark matter during cosmic inflation. This scenario involves an extension of the Standard Model through the introduction of a dark matter candidate/s and an anomalous U(1)_X gauge group. The general framework developed is found to be able to replicate both the observed matter-antimatter asymmetry and the dark-to-visible matter mass density. (Based on arxiv: 1503.02366)
Abstract
HBC 722 is a low-luminosity member of a small young cluster in the North America Nebula. It went into outburst in mid-2010, and following an initial brightening it is in a high phase since then. Spectroscopic arguments suggest that we witness an FU Orionis-type (FUor) outburst, and it is one of those extremely rare cases when the progenitor was a well known object. Even in the high state, HBC 722 is an order of magnitude less luminous than prototypical FUors, which seems to contradict to many current explanations of the FUor phenomenon. In this talk I review our work on the characterization of HBC 722 in its quiescent phase, as well as our optical/infrared monitoring programme of the last years. The data offer a unique opportunity to follow the outburst in detail, and understand the related structural and temperature changes in the inner disk.
Abstract
Westerlund 2 is one of the most massive young star clusters known in the Milky Way. It is located in the Carina-Sagittarius spiral arm containing more than 80 O-Type stars. Therefore, Westerlund 2 is a perfect target to study star formation process and feedback in the presence of massive stars as well as the possible triggering of star formation in the surrounding clouds. With 4.16 kpc, the close proximity to the Sun, as well as the young age of less than 1.0 Myr allow us to study star formation in detail at a high spatial resolution and makes it possible to determine the mass function of the cluster close to its initial state.
We present results from our recent deep multi-band survey in the optical and near-infrared obtained with the Advanced Camera for Surveys and the Wide Field Camera 3 on board of the Hubble Space Telescope, covering an area of ~20 arcsec2.
Combining Hα and Paβ line observations we were able to create a high resolution pixel-to-pixel map of the color excess E(B-V)g of the gas. We demonstrated that, as expected, the region is affected by significant differential reddening with a median value of E(B-V)g=1.87 mag, which is caused by the still present gas and dust of the HII region RCW 49.
After separating the cluster members from foreground contaminants we obtained for Westerlund 2 a pronounced pre-main-sequence population including a distinct turn-on region. The distance was inferred from the dereddened color-magnitude diagrams using Padova isochrones. It is in good agreement with the literature value of 4.16±0.33 kpc determined with spectroscopic data. By fitting the zero-age-main-sequence to two-color-diagrams we derived a value for the total-to-selective extinction of RV=3.95±0.135.
Taking a closer look at the observations reveals that young objects still appear embedded in their natal gas cloud.
Analyzing the spatial distribution of stars using a spatial number density map and a fit of two 2D Gaussians, we found that Westerlund 2 consists of two clumps, namely the main cluster of Westerlund 2 and a less well populated one located to the North, the northern clump. We estimated the same age of 0.1-1.0 Myr for both clumps, thus we conclude that they are likely coeval.
Abstract
The Mu2e experiment at Fermilab will be reviewed. The experiment is a high-rate search for muon decay modes not expected to occur within the Standard Model of Particle Physics. Jose will briefly introduce the physics goals of the experiment, put in the context of previous and competing measurements and then review some of the technical challenges of the experiment.
August 2015
July 2015
Abstract
CLASH-VLT is a VIMOS Large Programme (PI: P. Rosati, Univ. Ferrara) that builds on the CLASH HST multi-cycle treasury programme to carry out a comprehensive spectroscopic campaign on 13 massive galaxy clusters at a median redshift of 0.4. Upon completion, it will provide spectra and redshifts for ~7000 cluster members.
Andrea will describe some of the results obtained with the CLASH-VLT data obtained and reduced so far. In particular, he will concentrate on the internal dynamics of galaxy clusters, as traced by cluster member galaxies. He will show that with 500 cluster members they constrain the cluster mass profile to a level of precision comparable to that obtained with gravitational lensing. This is now possible, for the first time, also for merging clusters, by going beyond the unimodal solution of the Jeans equation. Andrea will also present constraints on the orbits of galaxies in clusters, and, for the first time, on Q(r), the pseudo-phase-space density profile. Q(r) is believed to be a powerful tool to constrain the mechanisms of formation and evolution of clusters. By comparing the cluster total mass-density profile and the stellar-mass and number density profiles of cluster galaxies, they probe evolutionary mechanisms of galaxies in clusters. By comparing the kinematic and lensing determinations of cluster mass profiles, they directly probe the equation of state of dark matter. At the end of his talk Andrea will discuss future developments of this research that they will address once the CLASH-VLT data sample will be finalized.
Abstract
Supermassive black hole binaries (SBHBs) are thought to be a natural, if not inevitable, phase in scenarios where most massive galaxies host central black holes and undergo frequent mergers as they evolve. While there are convincing examples of kiloparsec-separation pairs, there is no robust evidence for the sub-parsec binaries that are expected to exist. The detection of this population would contribute important evidence in favor of the prevailing galaxy evolution scenarios, and is also of interest in other fields including gravitational wave astronomy. We have undertaken a systematic search for close SBHBs based on the hypothesis that the secondary black hole in the binary accretes at a much higher rate than the primary, and its emission lines are doppler shifted due to its orbital motion (analogous to a single-line spectroscopic binary). Our sample of 88 candidates is therefore selected from z<0.7 SDSS quasars via substantial (>1000 km/s) shifts of their broad H-beta lines relative to their systemic redshifts. I will present an update on our efforts to evaluate the credentials of the candidates, including new radial velocity measurements from the spectroscopic monitoring program and a comparison of the spectral variability of the binary candidates to the broader quasar population.
Abstract
Dynamical processes responsible for the ejection of massive stars from their birth-sites as high-velocity runaway stars may be responsible for the most powerful protostellar outflows. The OMC1 outflow, located immediately behind the Orion Nebula, may have been triggered by the dynamic interaction of a non-hierarchical system of massive stars that formed a compact binary, ejected the binary (suspected to be radio source I) and the 15 Solar mass BN object, and released ~10
48 ergs of energy about 500 years ago. Explosive outflows similar to Orion may be associated with the ejection of runaway stars, produce IR-flares with luminosities between novae and supernovae, and have profound feedback impact on their parent molecular clouds.I will present multi-conjugate adaptive optics imaging with the Gemini-South 8-meter telescope at 0.06" resolution images of the 2.12 micro-meter H2 and 1.64 micro-meter [FeII] emission from the shock-excited fingers and results from or ALMA Cycle 2 observations of CO and the continuum with 1" angular resolution. I will also discuss the first results of a Spitzer warm-mission program (SPIRITS) which is searching for IR-only transients, some of which may be similar to the Orion event, in ~200 nearby galaxies.
Abstract
The Excellence Cluster Universe organizes the Research Area F Science Day. Area F deals with the research question "What processes drive the building of the visible structures in the Universe?". Experimental as well as theoretical Cluster scientists and students who are active in this field come together to present current research results and developments.
Organizers: RA-F leaders Prof. Barbara Ercolano (LMU) and Dr. Vincenzo Mainieri (ESO) and the team of the Excellence Cluster Universe
Abstract
The Excellence Cluster Universe organizes the Research Area D Science Day. Experimental as well as theoretical Cluster scientists and students who are active in the field of "What are the phase transitions in the early Universe?" come together to present current research results and developments.
Organizers: RA-D leaders Prof. Siegfried Bethke (MPP) and Prof. Laura Fabbietti (TUM) and the team of the Excellence Cluster Universe
Abstract
The Aim of This Conference
Measuring the distribution of matter in the universe as a function of time and space is a powerful probe of cosmology.
It offers a unique test of how gravity works on scales much greater than the conventional tests of General Relativity, and is considered as the most sensitive probe of the origin of the cosmic acceleration. Statistical properties of matter distribution can also constrain the nature of initial fluctuations, hence the physics of inflation, and the mass of neutrinos.
Observations of the large-scale structure of the universe are improving rapidly, pushing the survey volume and redshifts to unprecedented territory with various tracers such as passive and emission-line galaxies, quasars, dusty galaxies, Lyman-alpha forests, 21-cm line emissions, and gravitational lenses.
The rapid growth in the survey data demands much improved theoretical understanding of the large-scale structure. Unlike the cosmic microwave background fluctuations, the distribution of matter is non-linear, and thus we need a combination of non-linear theories and numerical simulations to properly interpret the existing and upcoming data.
This conference is organised in a unique time, in which the new generation of large-scale structure surveys have started/are starting to acquire data (e.g., eBOSS, VIPERS, DES, HSC/PFS, HETDEX, eROSITA and eventually Euclid and SKA), and we are witnessing a rapid progress in the theoretical understanding. We propose to bring together leading experts in both theory and observations of the large-scale structure of the universe to discuss the recent progress and future directions.
Abstract
Mu-Chun will discuss the origin of CP violation in settings with a discrete (flavor) symmetry. In particular, she will show that certain discrete symmetries clash with CP in the sense that, in generic settings with such symmetries, one cannot consistently define a proper CP transformation. For such discrete symmetries, CP violation can be purely group theoretical, leading to physical effects such as particle decay asymmetry.
Abstract
Alex will discuss recent work to present a novel Bayesian methodology for detecting halos of different masses in galaxy survey observations, whilst jointly quantifying the corresponding uncertainties. This methodology first uses the previously published HADES algorithm to create an ensemble of realisations of the matter density field throughout the survey volume. Using an N-body simulation to relate the density field to halo mass, we then use a Bayesian chain rule to build up maps of the detection probability of halos about specific mass thresholds. Demonstration of the methodology using a realistic galaxy mock catalogue shows an excellent agreement between the peaks in the probability maps and the positions of the dark matter halos. We conclude that this method is a promising novel tool for analysing observations of the large-scale cosmic web.
Abstract
High redshift galaxy protoclusters are the precursors of today’s massive clusters; the sites of formation of the most massive galaxies in the present-day Universe. In this talk I will examine the formation history of massive galaxies within high redshift protoclusters. We have obtained a sample of 37 dense clusters and protoclusters at 1.3<z<3.2 from the Clusters Around Radio-Loud AGN (CARLA) survey. We use optical i′-band, and infrared 3.6 and 4.5micron images to statistically select sources within these protoclusters and measure their average observed i′ – [3.6] colours. We find the abundance of massive galaxies within these overdensities increases with decreasing redshift, suggesting these objects form an evolutionary sequence, with the lower redshift (proto)clusters having similar properties to the descendents of those at high redshift. We have found that high redshift protocluster galaxies have an observed i′ – [3.6] colour which diverges from predictions at z>2. Taking the full cluster population into account, I will show that the formation of stars within the majority of massive cluster galaxies occurs over at least 2 Gyr, and peaks at z~2-3. The average i′ – [3.6] colours also imply that the star formation in these massive galaxies must have been rapidly terminated to produce the observed red colours. Finally, I will show that massive galaxies at z>2 must have assembled within 0.5 Gyr of them forming a significant fraction of their stars. This means that the formation mechanism of massive galaxies in clusters is redshift dependent: at z>2, few massive galaxies formed via dry mergers, whereas at z<2 dry merging is a more important formation mechanism.
Abstract
The Excellence Cluster Universe organizes the Research Area G Science Day. Experimental as well as theoretical Cluster scientists and students who are active in the field "Origin of the cosmic chemical elements and the compositional evolution of the universe" come together to present current research results and developments.
Organizers: RA-G leaders Prof. Roland Diehl (MPE) and Dr. Bruno Leibundgut (ESO) and the team of the Excellence Cluster Universe
Abstract
Quasar feedback on host galaxies in the form of powerful winds is invoked as a key mechanism to quench star formation in massive galaxies, but direct observational evidences are still scarce and the debate on the physical origin of the observed phenomena is still open. Marcella will first review the evidences we have for the presence of outflowing winds in galaxies and AGN at both low and high-z, at all spatial scales (from the accretion disk to the edges of the galaxies). Then she will present recent results from X-shooter and SINFONI observations of a sample of obscured QSOs at z~1.5 from the COSMOS survey, expected to be caught in the transitioning phase from starburst to AGN dominated systems. Their analysis suggests that the AGN rather than the on-going star-formation may be the major driver for the presence of the observed broad and shifted components. Marcella will also present unambiguous evidences of the effect of feedback in the host galaxy from studies of the ionised and molecular gas content of one of these powerful QSOs, based on SINFONI and PdBI data.
Abstract
Scientific Rationale
Mass loss from cool Asymptotic Giant Branch and Red Supergiant stars inputs large amounts of material to the ISM (10-7 to 10-4 Msunyr-1) and leads to the formation of Planetary Nebulae and Supernovae. It is therefore an important process for understanding both galactic ecology and stellar lifecycles. Recent years have seen significant advances in observations and theory of late stages of stellar evolution. Thanks to ALMA, VLTI and other recent telescopes/arrays, spectral lines and dust can now be resolved on scales down to the size of the stars themselves. The new data provide an opportunity to revisit outstanding questions of late stellar evolution: how is mass loss driven in AGB and RSG stars, what is the role of magnetic fields in their evolution, and what is the effect of binarity?
The meeting is planned for when ALMA Cycle 1, and some Cycle 2, results will have been released and VLTI is currently transforming to 2nd generation instruments (MATISSE, GRAVITY) and becoming an imaging machine (e.g. PIONIER). These telescopes provide complementary, high spectral and spatial resolution observations of different layers of the stellar atmosphere and wind species, and this workshop will exploit their synergies for the study of AGB and RSG stars. At the spatial scales probed, temporal variability and kinematical study of the above-mentioned processes are also possible.
In addition, project planning for ALMA, future facilities and instruments such as the E-ELT, mm/submm-VLBI, and a possible extension of VLTI imaging capability and 3rd generation VLTI instruments can take place.
Abstract
The series of lectures will focus mainly on the evolution, explosion and nucleosynthesis
of massive stars. The course will cover a variety of aspects related to the topic, starting
from the basic concepts of stellar evolution and nucleosynthesis to presupernova evolution,
supernova explosions and PopIII core-collapse supernovae. The course is mostly intended
for PhD students and post-doctoral researchers, or for whomever would like to brush-up
his/her knowledge on these topics.
The tentative breakdown of the lectures is as follows:
Lecture 1 - Tuesday, 30 June:
Introduction
Stellar Structure Basics
Thermonuclear reactions
Hydrostatic Nuclear Burning Stages
Lecture 2 - Wednesday, 1 July:
Presupernova Evolution of Massive Stars
Role of Mass Loss
Role of metallicity
Role of rotation
Lecture 3 - Thursday, 2 July:
Explosive Nucleosynthesis
Hydrostatic and Explosive Yields
Lecture 4 - Friday, 3 July:
Presupernova evolution and explosion of zero metallicity massive stars
Comparison with observations
Video
Abstract
Variability from black holes - both stellar mass and supermassive - has been studied for many years, but we have only recently pieced together the physical origin of the variability. Developments in multiwavelength monitoring and X-ray spectral-timing now allow us to study the causal relationship between variations of different spectral components, allowing a direct link to the physics of the emitting regions close to the black hole. I will describe the recent advances in this area which reveal some surprises about the role of the turbulent accretion disc in producing the variability, give clues to the nature of the mysterious quasi-periodic oscillations and show the promise of new X-ray spectral timing techniques to map the emitting regions closest to the event horizon.
Video
Abstract
The series of lectures will focus mainly on the evolution, explosion and nucleosynthesis
of massive stars. The course will cover a variety of aspects related to the topic, starting
from the basic concepts of stellar evolution and nucleosynthesis to presupernova evolution,
supernova explosions and PopIII core-collapse supernovae. The course is mostly intended
for PhD students and post-doctoral researchers, or for whomever would like to brush-up
his/her knowledge on these topics.
The tentative breakdown of the lectures is as follows:
Lecture 1 - Tuesday, 30 June:
Introduction
Stellar Structure Basics
Thermonuclear reactions
Hydrostatic Nuclear Burning Stages
Lecture 2 - Wednesday, 1 July:
Presupernova Evolution of Massive Stars
Role of Mass Loss
Role of metallicity
Role of rotation
Lecture 3 - Thursday, 2 July:
Explosive Nucleosynthesis
Hydrostatic and Explosive Yields
Lecture 4 - Friday, 3 July:
Presupernova evolution and explosion of zero metallicity massive stars
Comparison with observations
Video
Abstract
Active Galactic Nuclei (AGN) play a key role in the formation and evolution of galaxies through so-called AGN feedback. Quantifying the magnitude (and even the sign) of this feedback, however, is difficult. Two effects play a key role in determining feedback efficiency: (1) the kinetic power of AGN jets, which set how much energy is available for feedback; and (2) the chronology of the AGN-starburst connection, which determines how promptly this energy is delivered to the surrounding gas.
Stas will discuss different ways of measuring AGN kinetic power, and outline a recent approach in which they combine models describing the dynamical evolution of observable radio AGN properties with semi-analytic galaxy formation models. He will show how this technique can be used to derive the physical properties of low-redshift AGN, shedding light on processes driving AGN triggering and feedback.
Stas will also present the latest results from their multi-wavelength study of a morphologically-selected sample of early-type galaxies with dust lanes, drawn from Galaxy Zoo. He will argue that gas-rich galaxy interactions are responsible for triggering radiatively efficient AGN in the local Universe. Using such a clean, morphologically-selected sample allows them to reconstruct the timeline linking star formation and AGN activity. They find that merger-triggered star formation precedes AGN triggering. These findings have important implications for both observational signatures of merger-triggered star formation and AGN activity, and the efficiency of AGN feedback.
Abstract
The series of lectures will focus mainly on the evolution, explosion and nucleosynthesis
of massive stars. The course will cover a variety of aspects related to the topic, starting
from the basic concepts of stellar evolution and nucleosynthesis to presupernova evolution,
supernova explosions and PopIII core-collapse supernovae. The course is mostly intended
for PhD students and post-doctoral researchers, or for whomever would like to brush-up
his/her knowledge on these topics.
The tentative breakdown of the lectures is as follows:
Lecture 1 - Tuesday, 30 June:
Introduction
Stellar Structure Basics
Thermonuclear reactions
Hydrostatic Nuclear Burning Stages
Lecture 2 - Wednesday, 1 July:
Presupernova Evolution of Massive Stars
Role of Mass Loss
Role of metallicity
Role of rotation
Lecture 3 - Thursday, 2 July:
Explosive Nucleosynthesis
Hydrostatic and Explosive Yields
Lecture 4 - Friday, 3 July:
Presupernova evolution and explosion of zero metallicity massive stars
Comparison with observations
Video
June 2015
Abstract
When comparing the gas content of galaxies with their current star
formation rate, it has been found that the gas consumption time scale is
much smaller than the age of galaxies. This discrepancy leads to the
conclusion that galaxies need to replenish their gas reservoirs to
sustain star formation.
In order to investigate this process of gas replenishment in more detail
we target galaxies that contain at least 2.5 times more atomic hydrogen
(HI) than expected from their optical properties using scaling
relations. For this set of galaxies, we are building a rich data set
consisting of deep HI interferometry (Australia Telescope Compact
Array), optical integral field spectroscopy (WiFeS spectrograph on the
SSO 2.3m telescope), deep imaging (DECam) and publicly available
photometry from GALEX (ultraviolet), WISE (infrared) and DSS-II
(optical). This data set will enable us to distinguish between multiple
scenarios that might lead to an excess in HI content, among them a phase
of elevated gas accretion, minor mergers or an inefficient conversion of
gas into stars. In a next step it allows us to investigate the
respective scenario in more detail.
In my talk I will first introduce the survey, then compare the HI excess
galaxies to the general galaxy population with respect to star formation
and stellar mass and finally present first results of the more detailed
analysis of the ATCA HI data combined with the optical IFU spectroscopy.
Abstract
The series of lectures will focus mainly on the evolution, explosion and nucleosynthesis
of massive stars. The course will cover a variety of aspects related to the topic, starting
from the basic concepts of stellar evolution and nucleosynthesis to presupernova evolution,
supernova explosions and PopIII core-collapse supernovae. The course is mostly intended
for PhD students and post-doctoral researchers, or for whomever would like to brush-up
his/her knowledge on these topics.
The tentative breakdown of the lectures is as follows:
Lecture 1 - Tuesday, 30 June:
Introduction
Stellar Structure Basics
Thermonuclear reactions
Hydrostatic Nuclear Burning Stages
Lecture 2 - Wednesday, 1 July:
Presupernova Evolution of Massive Stars
Role of Mass Loss
Role of metallicity
Role of rotation
Lecture 3 - Thursday, 2 July:
Explosive Nucleosynthesis
Hydrostatic and Explosive Yields
Lecture 4 - Friday, 3 July:
Presupernova evolution and explosion of zero metallicity massive stars
Comparison with observations
Video
Abstract
For over 50 years, NASA has relied on advanced mirror technology development to enable space telescope missions: from Hubble to JWST. Currently NASA is engaged in technology development to enable even larger and more sophisticated future telescopes. This presentation reviews the needs for space telescopes which drives technology development; traces the history of mirror technology development from the 1957 to the present; and discusses potential future trends in mirror technology development. Specific technology areas include: evolution of mirror architectures, substrate material development, and improvements in optical fabrication and testing technology.
About the speaker: Dr. Stahl is a Senior Optical Physicist at NASA MSFC; the Astrophysics Division Deputy Assistant Director for Technology; and the James Webb Space Telescope (JWST) Optics Lead for the primary, secondary and tertiary mirrors.
Abstract
An overview of the nuclear arms race will be presented with emphasis on its history from inception to the present. Discussions about preventing proliferation and further use started in the secrecy of the Manhattan project for many of the atomic scientists. They continued in public during rapid cold war buildup into the present era of gradual arms control and the visionary call for abolition of nuclear weapons. The central role of the nuclear non-proliferation treaty as well as issues with Iran and North Korea will be presented. As time allows, impediments to arms control such as rapid launch deployment, weapon and delivery system modernization, and US-Russian tensions will be discussed. A personal outlook for the future will be presented.
About the speaker:
Aron Bernstein is Professor of Physics Emeritus at MIT where he has been on the faculty since 1961. He has taught a broad range of physics courses from freshman to graduate level. His research program has been in nuclear and particle physics, with an emphasis on studying the basic symmetries of matter, and currently involves collaborations with University and government laboratories, and colleagues in many countries.
Since 1969 he has been active in the area of nuclear arms control. His teaching has included seminars on the nuclear arms race with Phillip Morrison, co-organizing a recent student seminar on nuclear proliferation, and being the advisor to a student group on arms control.
Professor Bernstein chaired a Federation of American Scientists chapter at MIT and the MIT Faculty Disarmament Study Group and actively spoke out against the "star wars" anti-ballistic missile program from its inception. He worked with Henry Kendall and the Union of Concerned Scientists over a period of years, and continues to work with U.C.S. in its efforts to educate Congress on issues of arms control.
Professor Bernstein is a fellow of the American Physical Society and the American Association of Scientists. He has been awarded John Simon Guggenheim and Humboldt Senior Research Fellowships.
Abstract
Deep exposures with the Hubble Space Telescope (HST) have provided
the primary evidence that star-forming galaxies were present in the
first billion years of cosmic history. Sometime during this early
period the intergalactic medium transitioned from a neutral gas to
one that is fully ionized. How did this `cosmic reionization' occur
and were star-forming galaxies responsible? Recent imaging of deep
fields with HST's Wide Field Camera 3 in conjunction with ground-based
spectroscopy has provided important new insight into understanding
when reionization occurred and the role of early galaxies in the
process. Gravitational lensing by foreground clusters is providing
complementary evidence. I will review this rapid progress in our
understanding of what could be considered the last missing piece
in our overall picture of cosmic history and discuss the remaining
challenges ahead of future facilities such as E-ELT/TMT and JWST.
Abstract
I discuss the star formation history of the Milky Way, how its constituent components grew their stellar masses, with the context of what we know about distant galaxies. The evolutionary history of the MW provides interesting insights into why galaxies are dynamically hot in the early universe, what may "quench" galaxies, and how thin and thick disks grow.
Abstract
Small temperature and density fluctuations in the early Universe have grown into the cosmic web of dark matter and baryonic matter that we see today. Matter is distributed among large-scale filaments, punctuated by galaxy clusters at the intersection points of this web. Mapping the cosmic history of rich galaxy clusters provides fundamental information about both cosmology and galaxy evolution, motivating vigorous programs to search for large sample of clusters by several teams.
In this talk I will describe recent results from our surveys of clusters at 1.0 < z < 3. In particular, I will focus on the role of the environment in shaping the mass-size evolution of cluster galaxies and the evolution of galaxy stellar population properties.
Abstract
Cosmic rays in Milky Way-like galaxies represent only about a billionth of interstellar particles by number, but carry as much energy as the thermal particles and interstellar magnetic field. Although they are virtually collisionless, they can exchange energy and momentum with the thermal gas through scattering from magnetic fluctuations. This coupling can launch galactic winds, heat interstellar and intracluster gas, enhance magnetic buoyancy, and modify shocks. I will discuss the basis for cosmic ray - thermal gas coupling and some open issues.
Abstract
A common task at large scale facilities is to present to their funding bodies as well to the national society the research they conduct with their considerable budget. A similar expectation on public relations (PR) and dissemination concerns large EU funded projects as I3s or bigger consortia. Even though a consensus exists, that good communication is a fundamental part of innovation, the expectations from the funding bodies with regards to science communication activities are unclear, and a well-defined work programme is often missing.
The aim of the workshop is to bring together representatives of funding agencies (European and national) with facility and project managers to discuss what should be expected from scientific dissemination activities. Furthermore it should be a forum for PR and information officers to share experience of their work and gain insights into the expectations of funding bodies as well as from the general public.
Abstract
Supernovae are violent events at the end stage of the life of a star. They can either arise from the core collapse of a massive star or be a thermonuclear explosion. Thermonuclear supernovae (known as type Ia supernovae or SN Ia in short) can be used as distance indicators in cosmology and led to the discovery of the accelerated expansion of the universe. Moreover, there are several, interesting, unanswered questions regarding the physics of SN Ia, e.g. explosion mechanism, progenitor system, which also have potentially significant consequences for their use in cosmology. Dedicated studies of SN Ia at optical wavelengths have led to precise constraints on cosmological parameters. Detailed observations have demonstrated them to be a heterogeneous class of objects. The near infrared presents a new window for studying these explosions, both from the viewpoint of cosmology and understanding the physics of SN Ia’s. In this talk Suhail will summarize recent studies and his current work.
Abstract
The initial multiplicity of stellar systems is highly uncertain, but it provides an important constrain to the understanding of star formation. A number of mechanisms have been proposed to explain the origin of binary and multiple star systems, including core fragmentation, disk fragmentation and stellar capture. Observations show that protostellar and pre-main-sequence multiplicity is higher than the multiplicity found in field stars, which suggests that dynamical interactions occur early, splitting up multiple systems and modifying the initial stellar separations. Here we report observations of a wide-separation (1,000 au) quadruple system composed of a young protostar and three gravitationally bound dense gas condensations. These condensations are the result of fragmentation of dense gas filaments, and each condensation is expected to form a star on a time-scale of 40,000 years. We determine that the closest pair will form a bound binary, while the quadruple stellar system itself is bound but unstable on timescales of 500,000 years (comparable to the lifetime of the embedded protostellar phase). These observations suggest that filament fragmentation on length scales of about 5,000 au offers a viable pathway to the formation of multiple systems.
Abstract
Scientific rationale
Understanding the formation and evolution of galaxy groups is crucial to solving the general problem of galaxy formation, as groups contain most of the galaxies in the universe at the present day, and a most of the universal stellar mass is formed in groups. In addition, in the current bottom-up paradigm of structure formation, galaxy groups are the building blocks of more massive systems: they merge to eventually form clusters. As structures grow, galaxies join more and more massive systems, spending most of their life in galaxy groups before entering eventually the cluster environment. Groups of galaxies are special systems in an observational sense as well, as it is possible to probe both the stellar and hot gas components of these systems directly.
AGN feedback and massive galaxies
As highlighted in many recent theoretical papers, the properties of the hot gas and of the stellar component are intimately intertwined. In recent years, a growing number of authors have argued, based on the results of semi-analytic models of galaxy formation as well as hydrodynamic simulations, that feedback from supermassive BHs (the so called “radio mode” feedback) plays a crucial role in regulating the star formation rates of massive galaxies and suppressing the onset of catastrophic cooling of the hot gas in groups and clusters. However, the observational results are still inconclusive in this respect in the group regime. Groups have low gas fractions within their inner region and the radio AGN outbursts should have significant impact on their X-ray properties. Therefore, groups that have experienced strong heating episodes would be X-ray faint and are difficult to be studied in detail in X-rays. These systems would also be underrepresented in any group samples selected in the X-ray or by X-ray cavities with the strong contrast. In addition, groups showing sign of cool core do not host usually strong radio AGN. Most of these radio outbursts should generate strong shocks in groups (Mach number > 2). However, all reported shocks in groups are weak ones with Mach number of 1.5 - 1.7.
Do group galaxies evolve faster?
In the last decade a substantial effort has been devoted to the study of high redshift groups to investigate the possibility of a differential evolution of group galaxies with respect to field galaxies. A significant step forward was achieved thanks to the advent of very deep multiwavelength surveys conducted on several blank fields. In this context, the main outcome of these surveys is that group galaxies show a much faster evolution with respect to the field galaxy. For instance, the formation of the galaxy red sequence, which leads to the local dichotomy between red and blue galaxies, happens earlier in groups than in the field especially at the high stellar masses. It seems also that group galaxies undergo a substantial morphological transformation. Indeed, groups at z~1 host a transient population of "red spirals" which is not observed in the field. In parallel, the star formation activity of group galaxies seems to be suppressed in a more efficient way since z~1 than in other environments.
The open questions
Where are we now? Are the X-ray observations deep enough to let us finally observe X-ray under-luminous groups with strong radio relics? Are there any group cool cores with strong radio AGN at the center? Can we find strong AGN shocks in groups? In other words, can we confirm the theoretical paradigm of massive galaxy formation and the crucial role of “radio mode” AGN feedback? Do the X-ray selection provide an unbiased view of the relation between AGN radio properties and X-ray group properties? Are the current observations deep enough to probe the faint X-ray groups or do we need to wait for eROSITA and Athena+?
Is the group environment able to influence the properties of the whole group galaxy population? If this is the case, what is the environmental process responsible for changing the group galaxy morphology and quenching their star formation activity?
Abstract
Galaxy clusters are the largest and most recently formed cosmological objects in the universe, making them powerful laboratories for both cosmology and astrophysics. The current generation of multi-wavelength cluster surveys (including Planck, ROSAT and SDSS with follow-up observations by Chandra, HST and XMM-Newton space observatories) have dramatically increased the sample size and the image quality of observed galaxy clusters out to high-redshift. However, the statistical power of these surveys are limited by complex and still poorly understood cluster astrophysics that shape their observable properties and evolution. In this talk, I will review recent advances and challenges in our understanding of cluster astrophysics and discuss future prospect for the use of galaxy clusters as a cosmological probe.
Video
Abstract
Dark energy represents a mysterious component of the Universe which is commonly thought to cause accelerated cosmic expansion.
In summer 2013, a new project started to solve the mystery of dark energy. This is the Dark Energy Survey (DES), a project where the Excellence Cluster Universe is a member as well. Core of the five-year mission is the powerful 570-Megapixel Dark Energy Camera (DECam) mounted on the 4-meter Victor M. Blanco telescope at the National Science Foundation’s Cerro Tololo Inter-American Observatory in the Andes Mountains in Chile.
Recently, DES completed its second season of observations at the southern sky, now covering the full 5000 deg^2 survey footprint at varying depth (23.2-23.4 mag in the i-band). In this talk Tim will give an overview on the DES survey and collaboration and the rich variety of science that can be extracted from this data set. After introducing Weak gravitation lensing (WL) as a probe to constrain cosmology and dark energy, he will then focus on the DES WL analysis and on plans for the upcoming Year 1 analysis. Tim will conclude with an outlook on WL science from future satellite missions (Euclid and WFIRST) and from a potential suborbital, balloon-based telescope.
Abstract
After decades of effort the census of stars in the solar neighborhood (d<8 pc) is almost complete. But now, new challenges and new questions need to be addressed. Complete the census within 25 pc from the Sun is one of them, as it would give a more robust and statistically significant set of objects, including more massive stars and objects from different populations. Although the stellar regime is close to be complete, the field brown dwarf density, and its multiplicity, are still uncertain, as the discovery of hundreds of these objects in the last five years proves it. In this talk I will summarize the improvements in the field of nearby stars and brown dwarfs, and our effort to discover new objects towards crowded areas using the VVV survey, and characterize ultra cool dwarfs in the solar neighborhood using VO tools, spectroscopy and astrometry.
Abstract
Balmer lines in emission are most prominent features in Mira stars spectra and have a strong potential as a proxy to study the lower atmosphere’s dynamics. During my thesis, I accumulated spectropolarimetric observations of Balmer lines in emissions. As the shock is propagating outwards, linear polarization increases and evolves. Assuming that linear polarization arises from anisotropic scattering, it tells us something about the geometric structure of the shock as it propagates. Such a line of study is typically one to be undertook by interferometry. In 2012, Amber data on the Mira stars omicron Ceti and R Horologii have been collected, in which the Brackett γ is studied.
In general, the polarimetric and interferometric approaches are thought to be very complementary for this kind of studies. Spectropolarimetric observations are more convenient to realize but for the models we have to deal with complex radiative transfer theory. On the other hand, interferometry is not as easy to perform but we can resort to simple models to fit visibilities and phase closures.
May 2015
Abstract
Video
Abstract
Weak gravitational lensing is a tool for investigating the large-scale distribution of matter in the universe and for testing cosmological models through their influence on the expansion dynamics of the universe and the evolution of cosmic structures. The signature of gravitational lensing are correlations between the shapes of neighbouring galaxies: their images are distorted in a correlated way because their light reaches us along similar paths with correlated deflection by cosmic structures. There might be, however, intrinsic correlations in the shapes of galaxies due to the galaxy formation process or due to direct interaction of galaxies with ambient cosmic structures. Björn will try to illustrate the two processes and show ways in which future lensing surveys can be used in more than one way.
Abstract
To study the dust obscured processes of star formation and black hole accretion at the peak of the SFR and BHAR functions (z=1-3) during galaxy evolution and establish their role, as well as their mutual feedback processes, rest frame mid-to-far IR spectroscopy is needed. At these frequencies dust extinction is at its minimum and a variety of atomic and molecular transitions, tracing most astrophysical domains, occur. The future IR space telescope mission, SPICA, fully redesigned, will be able to perform such surveys in a synergic way with other missions at different frequencies (such as Athena).
Abstract
Galactic winds are the most dramatic form of feedback provided by massive stars. In the first part of my talk I will summarize the importance of galactic winds for the evolution of galaxies and the inter-galactic medium. I will briefly describe the physical processes that drive these winds, and give a short guided tour of the multi-phase wind driven from the local starburst galaxy M82. I will then describe how the properties of winds are typically incorporated in cosmological simulations and semi-analytic models. In the second part of my talk I report on recent work that has determined the dependence of the basic wind properties (outflow velocities, mass and momentum outflow rates) on the properties of the galaxy/starburst. These results are strongly at odds with some of the most popular wind prescriptions in simulations and models. In the third part of the talk I will describe observations of the impact of galactic winds on the circum-galactic medium. Finally, I will report on new observations that reveal how stellar feedback, including galactic winds, enabled early star-forming galaxies to re-ionize the universe.
Video
Abstract
If there is one thing in common throughout virtually all of modern astrophysics, that must be the importance of measuring the distance to celestial objects. In fact, hardly any physics can be done without knowing the distance to the objects being studied. Cepheid stars are arguably the best stellar distance indicators: they were key in establishing the nature of the Universe at the beginning of last century and will play a major role into the foreseeable future, as we gain more insight in the physics that regulates them and in the systematics that affect their properties.
In this talk Martino will review the physical properties of Cepheid and their numerous applications, from probes of galactic structure and evolution to their role in investigating the nature of cosmic acceleration.
Abstract
In the 21st century, detailed studies of individual stars have expanded beyond the solar neighbourhood thanks to large, deep Galactic surveys. I will focus in this talk on two surveys and their synergy that are exploring the "hidden" parts of stars and the Milky Way. The SDSS-IV/APOGEE Survey is using a multi-object, wide-field infrared spectrograph to measure chemistry and dynamics across the Milky Way, with particular emphasis on obscured regions. At the same time, asteroseismologists have used the Kepler satellite to reveal the interiors of stars through frequency analysis of their lightcurves. The Kepler Cygnus field provides an in-depth look at the stellar populations along the solar annulus, while the extended K2 mission is probing many lines of sight as it looks at ecliptic fields. I will discuss the view of the Milky Way emerging from these studies, including abundance mapping of disk and bulge, kinematics of the bar, radial mixing of stars, tagging of stellar populations, and the stellar history of the Milky Way.
Abstract
Galaxy evolution is usually measured through probing scaling relations and distribution functions and determining if and how they evolve through cosmic time. While this method is effective for the characterization of the bulk of the galaxy population it does not reveal how individual galaxies may have formed, nor does it allow us to trace directly the formation processes in galaxies. Furthermore, because galaxies grow through mergers and star formation over time, selecting similar galaxies between epochs based on measurements of luminosity or even stellar or total mass is fraught with biases that makes any inferred evolution highly suspect. One approach for understanding this problem is to use abundance matching, whereby galaxies are compared between different epochs based on their relative number densities. If galaxies retain their rank ordering in some property, such as stellar mass or halo mass, then this would be an effective method for determining how different galaxy populations evolve through time. In this talk I will discuss using simulation results to quantify how well we can utilise the abundance matching technique, and within what limits the assumptions of a stable rank ordering of galaxy masses remains valid up to z=3. I will then discuss the application of this method using data from the GNS, UKIDSS UDS, and CANDELS surveys to show how we can effectively use abundance matching to determine how the processes of galaxy mergers, in-situ star formation and gas accretion from the intergalactic medium are driving the formation of galaxies at z < 3.
Abstract
This talk is an overview to the topic black holes and is in particular dedicated to students working in the fields of astronomy as well as particle physics.
Black holes are solutions of Einstein's field equations in General Relativity. After presenting the most important black hole solutions and their features we will investigate techniques on how to detect black hole candidates in the cosmos. We will also discuss the role of black holes in stellar evolution and galaxy physics.
Finally, we will discuss black holes from the perspective of fundamental physics. What happens to matter swallowed by the black hole? Do black holes destroy information? Is it possible to produce black holes in modern particle accelerators?
Abstract
Star formation is a key physical process of baryonic matters, and plays crucial roles in driving galaxy formation and evolution. The observed relationship between star formation rates and gas masses, star formation law, offers a powerful empirical way in understanding star formation and is widely invoked in numerical simulations of galaxy formation and evolution. In the past decade, the rich multi-wavelength data of nearby galaxies have enabled well characterizations of this gas-SFR relationship. I will talk about our recent works about star formation law, and show that in addition to the gas density, other factors may also regulate star formation such as existing stars, metallicities etc. This challenges the traditional SFR-gas relationship, implying that different physical mechanisms may play roles in driving star formation during galaxy evolution.
Abstract
The European Space Agency's astrometry satellite Gaia was launched in December 2013 and started its scientific operations in July 2014 after an extended payload commissioning period. I will provide an overview of the Gaia mission, its first year of operations, and the status of the data treatment by the Gaia Data Processing and Analysis Consortium (DPAC). Preliminary results indicating the performance of Gaia at this stage of the mission will be shown. Finally, I look ahead at the Gaia data releases, showing what survey products can be expected and when. Gaia in a nutshell ------------------ Gaia is the European Space Agency mission which will provide a stereoscopic census of our Galaxy through the measurement of high accuracy astrometry, radial velocities and multi-colour photometry. Over the course of its five year mission will measure parallaxes and proper motions for every object in the sky brighter than magnitude 20 --- amounting to about 1 billion stars, galaxies, quasars and solar system objects. It will achieve an astrometric accuracy of 25 micro-arcsec at 15th magnitude and 500 micro-arcsec at 20th magnitude. Multi-colour photometry will be obtained for all objects by means of low-resolution spectrophotometry between 330 and 1000 nm. In addition radial velocities with a precision of 1--15 km/s will be measured for all objects to 16th magnitude, thus complementing the astrometry to provide full six-dimensional phase space information for the brighter sources. More information can be found at: www.cosmos.esa.int/gaia
Abstract
Understanding the process responsible for transforming star forming galaxies
into passive and quiescent systems is currently one of the hottest topics
in astronomy. I will discuss recent observational results probing different
mechanisms at work in different galaxies and at different epochs. I will
show that the analysis of the stellar metallicities in large samples of
local galaxies reveals that "strangulation" (i.e. the lack of gas inflows)
is responsible for quenching star formation in most galaxies. I will
discuss the possible mechanisms responsible for such starvation of galaxies.
Very likely the environment in which galaxies evolve plays a role, but it
is not the only culprit. Then I will shortly review multiwavelength
observations that have provided evidence for powerful starburst-driven
and AGN-driven outflows in galaxies. Certainly these outflows have a
profound impact on the evolution of galaxies, both locally and at high-z,
however such outflows are probably uncapable of completely quenching star
formation in galaxies. Yet, I will show that such massive outflows can
have an unexpected, positive effect on the evolution of galaxies, which
has been overlooked so far.
Abstract
Nicola presents orbital anisotropy and dark halo parameters of a sample of early-type galaxies (ETGs) for which hundreds of planetary nebulae (PNe) have been observed within the PN.S Elliptical Galaxy Survey. Recent analyses have shown that PNe closely follow the bulk of the stellar population and can be used in combination with long slit and integral field kinematics to constrain the mass and orbital distribution of early-type galaxies out to their outskirts (~6-10Re). Discrete tracers currently represent a powerful tool for the investigation of these otherwise inaccessible regions of galaxies with other standard techniques, where typical dynamical times are longer and we expect to measure the signature or recent evolutionary events. In particular, the possibility to infer the variation of the orbital distribution of stars in the galaxy halos is a strong observational test for galaxy formation scenarios than can be compared with predictions of hydrodynamical simulations. Finally, Nicola will discuss the dark matter concentration and virial mass results against the predictions of state-of-art cosmological simulation in the LambdaCDM cosmology defined by Planck cosmological parameters. All these evidence together will allow us to gain insight on the baryon and dark matter assembly in the halo regions of early-type galaxies.
Abstract
Large-scale surveys of embedded protostars show a spread in luminosities of more than four orders of magnitude, which is commonly explained as evidence of episodic accretion: protostars spend most of the time in a quiescent phase of accretion (low L), while gaining most of their mass in a series of short-lived bursts of strong accretion (high L). However, it is still unclear how strong these bursts, how often they occur, and how long they last.
We can use chemistry as a novel way to characterize episodic accretion. During a burst, the increased stellar luminosity heats up the entire envelope and causes the partial evaporation of ices such as H2O and CO. After the burst ends, the envelope cools down on timescales of 1--100 yr, but it takes 10^3-10^5 yr for the molecules to refreeze onto the cold dust. I will present the first two sets of spatially resolved observations of such chemical signatures of recent bursts: extended H13CO+ detected with ALMA in one low-mass protostar, and extended C18O detected with the SMA in 8 out of 16 low-mass protostars. I will combine these observations with comprehensive chemical and radiative transfer models to infer typical lifetimes and frequencies of episodic accretion bursts.
April 2015
Abstract
One of the primary motivations for Herschel was to explore star
formation in the distant Universe. To address this topic Herschel
invested significant fraction of its time in undertaking surveys
including the multi-tiered extragalactic survey, HerMES. HerMES
mapped around 400 sq. degrees in the best studied extragalactic fields
on the sky and has uncovered 100s of thousands of distant star
forming galaxies. In this talk I will review some of the key results
from HerMES. In particular the Herschel maps reveal most of the
cosmic infrared background and these and other basic statistical
measurements have constrained our view on galaxy evolution models. I
will summarise what we have learned about the cosmic history of star
formation. I will show how clustering measurements have been used to
reason that these distant star forming galaxies are the progenitors
of present day, massive galaxy, descendants. I will show how Herschel
has revealed new insights into the relation between star formation and
central supermassive +black hole accretion activity. Finally I'll
illustrate how Herschel is uncovering starburst galaxies when the
Universe was less than a billion years old.
Video
Abstract
Hydrogen is the building block of galaxies, critical for both star formation and galaxy evolution across billions of years. Until now, its distribution and properties in the distant Universe have remained largely unexplored due to the limitations of existing telescopes. The Australian Square Kilometre Array Pathfinder is an SKA-precursor radio interferometer located in the Boolardy desert of Western Australia, and has entered its science-commissioning stage as the Boolardy Engineering Testbed Array (BETA). Through our collaborations between the University of Sydney, the ARC Centre for All-Sky Astrophysics and CSIRO Astronomy and Space Science, BETA is completing initial surveys for associated and intervening hydrogen absorption in galaxies up to a redshift of 1, with these samples being used to inform the science strategy of the upcoming FLASH, which will blindly survey 150,000 galaxies for their hydrogen content. I will present the work currently being carried out by the FLASH team and our future plans, as well as an overview of ASKAP and its capabilities.
Abstract
24 April 2015 marks 25 years since the NASA/ESA Hubble Space Telescope was launched into orbit. Remarkably, the telescope is still working very well today and still at the cutting edge of astronomy research. This talk will review Hubble's history, from visionary thinking, through construction delays and launch, the discovery of optical problems, the dramatic servicing missions and finally the long career as one of the most powerful scientific discovery tools ever created. I will also review some of the highlights of Hubble science and what the future holds. Finally I will talk briefly about how Hubble has developed a remarkable following among the general public and how there has been a strong link with ESO throughout its long life.
Abstract
The goal of the workshop is to discuss ongoing work on molecular gas in the Central Molecular
Zone of our Galaxy being performed by all attending groups. The participants are invited to
shortly present their scientific results. The main focus of the workshop is to discuss the many
open questions concerning the extreme environment of the Central Molecular Zone and how to
tackle these with future plans and projects.
Abstract
The formation of the most massive stars affects our Milky Way
as a whole but at the same time, many of the physical processes
take place on very small spatial scales. This talk will highlight
recent results in that field covering large-scale Milky Way structures
and the locations of the high-mass star formation sites within our
home galaxy, as well as the small-scale physical and chemical
processes at place to actually build and form these high-mass stars.
Video
Abstract
Galaxy clusters can be a very powerful source of information for both cosmology and astrophysics, especially if results from both observations and numerical simulations are combined to this scope. In particular, the intra-cluster medium (ICM) is an optimal target for this, since it represents about 80 per cent of the visible, baryonic matter in clusters. A promising approach is to use numerical simulations in order to produce synthetic X-ray data, which makes the comparison between simulated clusters and real ones more faithful. In this way, we can address a number of interesting issues, constrain the success of the numerical modeling, but also predict the capabilities of up-coming X-ray instruments (such as Athena) to capture the observable signatures of the underlying physical processes taking place in galaxy clusters.
Abstract
Electric dipole moments (EDMs) are a sensitive probe for physics beyond the standard model of elementary particles. In the low-energy regime, promising systems in search for the ensuing spatial parity (P) and time-reversal (T) non-conserving interactions are diatomic molecules. In this talk Timo will focus on the theoretical challenges to the search for P- and T-violating effects in two classes of systems, neutral and ionic diatomics. Particular emphasis will be lain on the electron EDM, the scalar-pseudoscalar electron-nucleon interaction, and the nuclear magnetic quadrupole moment. Recent theoretical developments as well as theoretical results used in conjunction with experimental measurements in order to constrain P- and T-violating physics will be presented.
Abstract
Magnetars are believed to be the strongest magnets in the Universe, and show themselves via powerful X/gamma-ray steady and flaring emission. The energetics of such flares in our Galaxy second only the supernova explosions. In this talk I will first review the observational characteristics of these magnetic pulsars, their evolutionary relation with the "typical" neutron star population, and recent news in the field (i.e. the low-field magnetars and the Galactic center magnetar). I will then finish with some considerations on how the study of the Galactic population of magnetars might constrain their possible connection with Gamma Ray Bursts.
Abstract
Vanilla single-field, slow-roll inflationary theory predicts that primordial fluctuations in the universe were nearly Gaussian random. However some very well-motivated models specifically predict observably large non-Gaussianity. Measurements of primordial non-Gaussianity therefore represent a rare window into the physics moments after the Big Bang. Dragan will first review the history of measurements of non-Gaussianity from the cosmic microwave background (CMB) anisotropies over the past two decades. Then, he will review results obtained over the past five years showing the signatures of primordial non-Gaussianity in the large-scale structure (LSS). Finally he will discuss the current and forecasted future constraints on classes of models for primordial non-Gaussianity from the combination of the CMB and LSS, and how they probe the physics of the early universe.
Abstract
ALMA/Herschel Archival Workshop
The Herschel Space Observatory has produced high quality photometric and spectroscopic data in the wavelength range approximately 55 to 670 μm during its lifetime from 2009 to 2013. To date, all Herschel science data (~23,400 hours of observations, ~37,000 AORs), in addition to a variety of user-provided data products, are publicly available through the Herschel Science Archive. Meanwhile, the ALMA Science Archive is being populated with observations carried out in the first three ALMA observing Cycles, with more data becoming publically available by the day.
The higher frequency ALMA bands overlap with the lower frequency (longer wavelength) Herschel bands, and despite the huge difference in spatial resolution, Herschel sources provide ideal targets for ALMA follow up. Furthermore, with more and more ALMA data becoming publically available every day, the possibilities to further explore these two complementary datasets that cover the fields of planetary, Galactic and extragalactic astrophysics, increase manifold. However, Herschel and ALMA data differ greatly and in order to explore their full potential, the archival users need to be aware not only of the contents of the two archives but of the differences of the datasets, as well.
Many of the Herschel users are increasingly proposing for ALMA time, while a large fraction of ALMA users until now have not spent enough time in checking the Herschel archive to complement their science with Herschel observations.
The target audience are all astronomers that have already used data from either of the two facilities and would now want to expand their knowledge to the neighbouring wavelength regime.
Main Goals
The workshop focuses on the ALMA/Herschel Synergies and archival research, with the following scope and goals:
- Provide examples of science cases based on the combined use of Herschel & ALMA data, covering a broad range of astrophysical topics, from star formation to evolved stars to galaxies and cosmology.
- Promote mutual awareness of Herschel & ALMA data archive contents
- Show users how to explore, access and visualize Herschel & ALMA data products, including existing quick look data analysis tools
- Enable Herschel & ALMA archival science
- Assist users in the preparation of Cycle 3 ALMA proposals based on existing Herschel data.
Abstract
Over the past 15 years, detailed analyses of optical quasar spectra from the
Keck telescope and VLT have suggested possible evidence for cosmological
variations in the fine-structure constant, alpha. The joint dataset even
contained self-consistent evidence for variations across the sky, or large
spatial scales in the universe. It was long understood that, if these
effects were not real, not due to a varying alpha, then a complicated
combination of systematic effects was required to explain them. At the same
time, very similar analysis techniques, applied to molecular hydrogen
absorption in quasar spectra from the same VLT instrument, indicated no
variation in the proton-to-electron mass ratio. I will describe the recent
development of "supercalibration" techniques to precisely check the
wavelength calibration accuracy of such spectrographs, even using archival
data. These have uncovered subtle but ubiquitous systematic effects which
substantially weaken the previous evidence for variation in alpha. Similar
"supercalibration" checks may be vital for ensuring the accuracy of the next
generation of high-resolution spectrographs on the VLT and the 30-40-m
telescopes of the future.
March 2015
Abstract
In the present Universe, all stars born in cold clouds of molecular gas which inner and outer physical phenomena play a key role to set the star formation capabilities of the galaxies. The study of a molecular-dominated spiral galaxy as M51 (in particular through the PdBI Whirlpool Arcsecond Survey data) has underlined the importance of the ISM clump characterization to provide fundamental insight within the physics involved into the process of star formation. In the same way, however, it challenged the performance of the most advanced cloud identification method to date, indicating the need for new, more powerful tools.
Some of the limitations of commonly used algorithms can be overcome by considering the cloud segmentation problem in the broad framework of the graph theory. Additionally, the clustering analysis provides a natural and robust mathematical description of the molecular ISM discrete features that might be viewed as “Molecular Gas Clusters”.
In particular, the algorithm we designed (SCIMES - Spectral Clustering for Molecular Emission Segmentation) applies the spectral clustering approach to look for relevant objects within topological graphs of emission (dendrograms) from star-forming clouds. SCIMES appears especially useful for the cloud identification within complex molecular emission data cubes since, in contrast to other algorithms, it does not over-divide structures, faithfully reproducing the work of the human eyes.
Moreover, SCIMES introduces a new philosophy in the identification of the molecular clouds, where virtually every property of the molecular emission might be used for the ISM segmentation. This may be helpful for distinguishing between the dominant physical mechanisms responsible for the formation of those molecular clusters.
Abstract
The distribution and abundance of water ice in planet-forming disks are key to understanding how terrestrial planets obtain water-rich atmospheres and hydrospheres. Using Herschel Space Observatory PACS spectra, I have detected amorphous and crystalline water ice features in disks around proto-solar analog stars.
Detailed modeling of the disk emission and comparison with constraining geometry suggest that the ice emitting region is at disk radii >30, consistent with a proto-Kuiper belt. Vertically, the ice emits most below the photodesorption zone, consistent with Herschel observations of cold water vapor. Based on timescale arguments and the presence of thermally processed water ice at a cold disk location, I conclude that we are detecting debris from icy planetesimal collisions.
The measured ice abundance is less than ½ of the solar value. However, these disks are still gaseous; measurements of ice abundance in debris disks better reflect the ice content at the time of potential water ice delivery to terrestrial planets. The new VLT instrument, SPHERE, can observe water ice in near-infrared scattered light. I present results from science verification observations and discuss future developments to quantify the ice content available for delivery in the first 10-100 Myr of planet formation.
Abstract
In past years, large and deep photometric and spectroscopic surveys have significantly advanced our understanding of galaxy growth, from the most active time in the universe (z~2) to the present day. In particular, the evolution in stellar mass, star formation rate, and structure of complete galaxy samples have provided independent and complementary insights into their formation histories. In addition, detailed studies of the properties of distant galaxies have led to a better apprehension of the physical processes which govern galaxy growth. Nonetheless, many outstanding questions remain. In this talk I will give an overview of our current picture of galaxy growth over the past 11 billion years, discuss current challenges and outstanding questions, and introduce new and ongoing efforts to further unravel the formation histories of massive galaxies.
Abstract
Active Galactic Nuclei (AGN) are characterised by strong variability at all wavelengths.
We exploited the VST monitoring observations of the COSMOS and CDFS regions, performed within the SUDARE/VOICE surveys, to assemble a sample of AGN candidates based on variability. Variability selection does not make strong a-priori assumptions about the properties of the sources and can thus integrate and complete samples selected by other techniques.
We investigate the effectiveness and reliability of this selection method by comparing it with spectroscopic, X-ray and IR selected AGN samples, in order to predict the performance that can be expected by future monitoring surveys such as LSST.
Abstract
The joint U.S. and German Stratospheric Observatory for Infrared Astronomy (SOFIA), to develop and operate a 2.5-meter infrared airborne telescope in a Boeing 747SP, has now successfully obtained first science with 6 instruments. These instruments are the FORCAST camera in the 5 to 40 micron spectral region, the GREAT heterodyne spectrometer in the 63 to 240 micron spectral region, the HIPO occultation visible photometer, the FLITECAM 1-5 micron camera, the FIFI-LS 50-210 micron spectrometer and the EXES 5-28 micron high resolution spectrometer. An overview of the flying observatory, the instruments and the first science results will be presented. Future observing opportunities and participation in future instrument developments, over the 20 year lifetime of the observatory will be discussed.
Abstract
In recent years, precision measurements across cosmic time have led to a widely accepted cosmological paradigm for galaxy assembly and evolution, the cold dark matter (ΛCDM) model. Within this theory, galaxies form "bottom-up," with low-mass objects ("halos") collapsing earlier and merging to form larger and larger systems over time. Ordinary matter follows the dynamics dictated by the dominant dark matter until radiative, hydrodynamic, and star-formation processes take over. Although ΛCDM has had great success in explaining the observed large-scale distribution of mass in the universe, the nature of the dark matter particle is best tested on small scales, where its physical characteristics manifest themselves by modifying the structure of galaxy halos and their lumpiness. It is on these scale that detailed comparisons between observations and theory have revealed several discrepancies and challenged our understanding of the mapping between dark matter halos and their baryonic components. In this talk I will review some of the triumphs and tribulations of the theory. While the latter may indicate the need for more complex physics in the dark sector itself, emerging evidence suggests that a poor understanding of the baryonic processes involved in galaxy formation may be at the origin of these controversies.
Abstract
Binary compact object mergers are among the primary gravitational wave sources expected to be observed by the next generation of ground-based gravitational wave detectors. Mergers where one or both compact objects are neutron stars will further produce electromagnetic emission, and coincident observation of this together with gravitational wave emission could teach us much about the progenitor systems, test general relativity in the dynamical strong field regime, and help elucidate the nature of matter at nuclear density. I will discuss ongoing work modeling such mergers within the context of general relativity coupled to ideal hydrodynamics, focusing on black hole-neutron star and binary neutron star systems merging with sizable eccentricity. Large eccentricity is expected for mergers that occur following dynamical capture or 3-body interactions in dense cluster environments, and though they may be rarer than the traditional quasi-circular inspiral, they could exhibit strikingly different behavior, including zoom-whirl orbital dynamics and large amounts of unbound material for cases where the neutron star is tidally disrupted.
Video
Abstract
Abstract
Understanding the atmospheric and evolutive properties of Very Low Mass stars, brown dwarfs and gas giant exoplanets have been important challenges for modelers around the world since the discovery of the first brown dwarfs in the field (Nakajima et al. 1995) and in the Pleiades cluster (Rebolo et al. 1995). Early studies have provided rich insights into atmospheric physics, with discoveries ranging from cloud formation (Tsuji et al. 1996), methane bands (Oppenheimer et al. 1995) and ammonia bands formation (Delorme et al. 2008), to the formation of quasi-molecular KI-H2 absorption (Allard et al. 2007), and to disequilibrium chemistry (Yelle & Griffith 2001). New classical 1D models yield spectral energy distribution (SED) that match relatively well that of M dwarfs, brown dwarfs and young gas giant exoplanets despite these complexities. These models have for instance explained the spectral transition from M to L, T and now Y brown dwarf spectral types (Allard et al. 2013). However, in presence of surface inhomogeneities as revealed recently for a nearby brown dwarf (Crossfield et al. 2014), the SED may well fit exactly, but the model parameters could be far from exact, e.g. with the effective temperature by several hundred kelvins too cool in the case of dusty brown dwarfs and young gas giant exoplanets!
On the contrary, recent developments (revises more complete molecular opacities, revised solar abundances, calibration of the mixing length) have led the to a spectacular improvement of M Dwarfs model atmospheres and synthetic spectra, and therefore to a better knowledge of the Teff-scale of M Dwarfs (Rajpurohit et al. 2013) which has recently been confirmed by the study of 160 M dwarfs (Mann et al. 2015)! This is promising at a time where planets are being searched around M dwarfs. New evolution models for M Dwarfs have therefore been recently published (Baraffe et al. 2015).
I will review the progress achieved in reproducing the spectral properties of very low mass stars, brown dwarfs/gas giant exoplanets, and review progress in modeling more accurately their atmospheres using Radiation HydroDynamical (RHD) simulations.
Video
Abstract
Programme:
09:40-10:00 - Morning Coffee and Introduction to Event.
10:00-10:30 - Susanne Braun (Psychologist LMU): "Gender stereotypes - how they impact the selection and evaluation of women in the workplace"
10:30-10:55 - Christiane Helling (Astronomer St. Andrews): "Gender equality in Astronomy in Germany and UK"(*)
10:55-11:20 - Francesca Primas (Astronomer ESO): "The `Women in Astronomy' working group of the IAU"(*)
11:20-11:45 - Michele Peron (Director of DoE, ESO): "Status of Women in DoE and dealing with the problems from its roots (girl's day)"(*)
11:45-12:10 - Discussion and closing remarks
12:10-12:50 - Finger food
(*) Titles are subject to changes.
Abstract
While Astronomy in Algeria is in full development, the only existing facility is Algiers Observatory which was built in 1890 by the French. Located in the heart of the capital, it is no longer suitable for astronomical observations. In order to establish a new observatory, we sought potential sites in Algeria and the Aures area (2000 m of altitude) was selected. In this presentation, I will discuss the reasons that led us to make this choice, and ongoing projects to establish the first post-independence Observatory. We will also discuss scientific issues and perspectives of the future Observatory, as well as other ongoing astronomical projects in Algeria.
Abstract
Recent work on understanding the origin of radio and X-ray emission from ultra-cool stars will be presented. One of the major open questions is the origin of free electrons/charges to be accelerated in a global magnetic field. Brown dwarfs can be fast rotators and they have strong magnetic field. But their atmospheres are considerably cooler than solar-mass stars, and Brown dwarfs do not follow the Guedel-Benz relation where Lx ~ Lradio. I will discuss recent progress in our understanding of ionisation processes in ultra-cool atmospheres where cloud formation plays an important role. The associated discharge processes (e.g. lightning) will have a role to lay in triggering the formation of the first biomolecules also in extrasolar atmospheres.
February 2015
Abstract
Acceleration of the universe has now been confirmed by a number of independent cosmological probes and is firmly established as a basic ingredient in the present-day universe. Yet the physical mechanism behind the acceleration - that is, the nature of dark energy - remains one of the great mysteries of modern physics. Given the increasingly impressive precision of cosmological measurements, an obvious question is whether we can improve our understanding of what drives the acceleration. I will review the current state of affairs, and present some recent developments on how to use measurements to rule out whole classes of explanations for dark energy.
Abstract
Stellar halos are ubiquitous in luminous galaxies, but because of their faint surface brightness the detailed study of their physical properties has been difficult and, until recently, confined largely to the Milky Way (MW) and Andromeda. Since the advent of large cameras and surveys, both from ground and space, our knowledge of stellar halos is increasing. Several late and early-type galaxies had stellar halo properties traced out to hundred kiloparsecs or beyond, revealing very low luminosity extended stellar structures similar to halos of our own MW and our closest neighbor, the Andromeda galaxy.
Observations show that these halos have complex morphologies with multiple stellar components, complex kinematics and substructures that indicate past history of mergers. These morphologies resemble the density maps from cosmological simulations of galaxy formation in a hierarchical universe and a large amount of effort is invested to try to understand how we go from a qualitative resemblance to quantitative measurements and frequencies of these substructures.
This workshop will bring together theorists and observers to discuss the results from the space and ground-based surveys of stellar halos in disks and ellipticals as well as from simulations. The properties of the Milky Way halo will also be discussed as representative of those of a halo around a spiral disk galaxy, with the main focus of the workshop being on extragalactic stellar halos. The aim is to review our knowledge (or lack thereof) about the physical properties of stellar halos and their origin in the context of cosmological predictions.
Abstract
The salience of satellite dwarf galaxies for understanding galaxy formation in a cosmological context has been made all the more evident in the past decade with the discovery of numerous faint Local Group galaxies. These faint systems are not only important to understand the faint end of galaxy formation but also their distribution around their host can test the hierarchical formation induced by the favored cosmological paradigm. I will review our successful effort to mine the two most ambitious surveys of the surroundings of the Milky Way and Andromeda galaxies, Pan-STARRS1 and PAndAS, for numerous new dwarf galaxies, before presenting the updated tally of MW/M31 satellites and what they are starting to tell us about galaxy formation in a LCDM universe.
Video
Abstract
With the advent of large surveys such as the SDSS and 2dF it has become possible to study in detail quasar clustering in the universe. Although not equal in numbers to galaxy surveys, the fact that luminous quasars are observable over large cosmic epochs enables a direct probe of the dark matter distribution. In the hierarchical clustering scenario, more massive galaxies harbouring the most massive black holes (BHs) cluster more strongly than less massive galaxies. A picture that is suggested by observations in the local universe, where most massive BHs are hosted by the most massive galaxies. However, this is not what is observed in clustering studies, where a weak dependency on luminosity is observed and implies that host halo mass and quasar luminosity do not follow a tight correlation, and both luminous and faint quasars reside in a broad range of host masses. We investigate the clustering of radio-quiet quasars (RQQs) and radio-loud quasars (RLQs) drawn from a joint use of the SDSS and FIRST surveys as function of radio-loudness and BH virial mass.
In this talk, we will discuss our clustering measurements and whether the simple idea that massive BHs are highly clustered is tenable and the implications for our current view of quasar clustering.
Abstract
Abstract
What is the nature of dark energy and dark matter? I will describe two astronomical observations based on strong gravitational lensing that can address this question in a novel way. In the first part of talk, I use as cosmic "standard rods" strong gravitational lenses where the background source is variable in time and the foreground deflector is a massive galaxy. I will illustrate recent advances in modelling techniques and data quality that enable a 6-7% measurement of absolute distance from a single gravitational lens. I will show that results from just two systems yield constraints on the equation of state of dark energy and flatness comparable to those obtained with the best probes. In the second part of the talk I will discuss the use of strongly lensed galaxies and quasars to detect the presence of dark subhalos independent of their stellar content. This observation tests a fundamental prediction of the cold dark matter model, i.e. that galaxies should be surrounded by large numbers of dark satellite subhalos. Proof that such satellites do not exist would force a revision of the model in favor of more exotic alternatives like warm dark matter. I will then conclude by discussing the bright prospects of studies of the dark sector using strong gravitational lensing.
Video
Abstract
This presentation will take you for a quick walk through the Universe connecting its coldest and hottest objects.
One of the important challenges in cosmology is to explain the formation of structure in the Universe. Cold dust absorbs a large fraction of the UV and optical light from stars and transforms it into infrared and millimetre wavelength radiation. The cool and dusty sites in the Universe help to form molecules, even organic compounds. These molecular clouds are actually nurseries where stars form and evolve.
How do you investigate these cold, dark places? Nature itself comes to the rescue, sending us bursts of very hard Gamma radiation that originate in supernovae exploding in distant galaxies. These flashes “illuminate” our nearby dust clouds, enabling us to look deep inside these otherwise opaque clouds. In this way we can investigate what’s going on in there and find out what the dust grains are like.
Abstract
A renaissance is taking place in optical and radio astronomy due to application of rapidly evolving commercial technology. Moreover, by all accounts (including Astro2010, The Astronomy and Astrophysics Decadal Survey), this decade is regarded as the decade of time domain astronomy. The dynamic radio sky is seen as a frontier area in astrophysics, ripe for discovery. The synergy between optical and radio astronomy, such as the joint VLA-PTF collaboration, have proved to be fruitful. This includes the earliest radio observation of a Type Ia SN, systematic measurements of circumstellar matter close to the progenitor of core-collapse SNe, and a possible discovery of a new type of relativistic explosion. Furthermore, radio observatories are now taking the role of discovering transients independently. A new generation of radio facilities is being built at decameter and centimeter wavelengths and all of them have identified the exploration of the time domain as Key Science. These include, for example, the LOFAR Transient KSP, ASKAP VAST, MeerKAT ThunderKAT, and WSRT APERTIF. In my talk I will discuss what we have learned in recent years from observations of the dynamic radio sky and will briefly present the future of time-domain radio astronomy.
Abstract
A picture arises where galaxy formation is fed by inflows of gas from
the inter-galactic medium (IGM), counteracted by strong galactic
winds, which in concert establish the growth rate of gas and stars
within galaxies at all cosmic epochs. These processes can be
collectively described as a “baryon cycle". I will present results on
UVES observations of the neutral gas reservoir for star formation, the
kinematics of gas around galaxies probed with IFU SINFONI and
X-Shooter and prospects to detect the circumgalactic medium (CGM) in
emission with purpose-built facilities. I will finally cover future
prospects in this field with the forthcoming Extremely Large optical
Telescopes.
Video
Abstract
The James Webb Space Telescope (JWST) is a large (6.5 m), cold (<50 K), infrared optimized space observatory that will be launched in 2018, and is NASA's highest priority for science. JWST has four instruments covering 0.6 to 28 micron, with scientific capabilities that include deep imaging, coronography, and powerful spectroscopy including multi-object, integral field, and exoplanet transit spectroscopic modes. As the JWST Project Scientist with expertise in planetary science, I will highlight the scientific capabilities of this powerful new observatory to study our own solar system, and briefly highlight other key science goals that include solar systems in formation, to the first generation of galaxies that formed after the Big Bang. I will summarize technical progress and mission status, and discuss how scientists can propose scientific observations with JWST.
January 2015
Abstract
The Planck collaboration releases the results and data from the full mission including polarisation. The Planck space mission has fulfilled its initial goal of extracting essentially all the cosmological information in the temperature map of the Cosmic Microwave Background. It has also detected the polarisation cosmological signals with unprecedented sensitivity over the whole sky. The results of the Planck collaboration papers to appear soon will be presented. They bring a determination of the cosmological parameters and support for the standard Lambda CDM model independent from the intensity data. They also bring results relevant for the physics of the primodial universe as well as particle physics. The polarised foreground emission from interstellar dust has been mapped with a spectacular accuracy. The claim for detection of primordial gravity waves from the BICEP2 team using CMB data aquired at south pole will be discussed in the light of the the dust B modes signal observed by Planck.
Abstract
Microwave background measurements have revolutionised cosmology, telling us a great deal about the composition and evolution of the Universe. Most analyses focus on the power spectrum of the fluctuations, but there is potentially much more to be gained by going beyond such a radical compression of the data; primordial non-Gaussianities could tell us much about the early universe. However, before we can interpret any signal as primordial, it is essential we understand the intrinsic non-Gaussianity that arises along the way, through the non-linear evolution of perturbations. This talk will focus on the non-Gaussianity and B-modes that arise naturally through the non-linear evolution of the microwave background.
Abstract
Einstein's General Relativity (GR) invented 100 years ago successfully describes gravitation. An algebraic extension of GR to pseudo-complex (pc) variables has been proposed, called pseudo-complex General Relativity (pc-GR). One of the important consequences of pc-GR theory is the presence of a field with repulsive properties. This has the effect that for very large masses the gravitational collapse is stopped and something what we call a “gray star” is formed instead of a black hole. We have performed ray-tracing simulations based on the pc-GR theory and standard GR for Sgr A* for different accretion scenarios and viewing angles for the observer. The simulated pc-GR images are clearly different from GR ray-tracing images. This provides the strongest test of GR theories. In addition we have simulated Fe K line profiles for both theories. As pc-GR discs are brighter, the integrated line flux is larger in pc-GR. The line profiles are clearly different from standard GR. This offers a second robust measurement to test pc-GR versus GR.
Abstract
I will present the single-dish and interferometric dust and molecular line images towards a specific type of stellar cluster-forming molecular cloud, namely the hub-filament system. We found that the overall geometry of molecular gas filaments converging to clumpy rotating gas toroid is present in molecular clouds in extremely broad ranges of cloud-mass and luminosity. I will also briefly mention how ALMA will potentially lead to a breakthrough in this subject.
Abstract
The magnetic field strength at birth has long been considered a fundamental property in determining the evolutionary path of a neutron star (NS). Objects with very high fields, collectively known as magnetars, are characterized by high X-ray quiescent luminosities, outbursts, and, for some of them, sporadic giant flares. While the magnetic field strength is believed to drive their collective behaviour, however, the diversity of their properties, and the observation of magnetar-like bursts from 'low-field' pulsars, has been a theoretical puzzle. In this talk, I will discuss results of long-term MHD simulations which, by following the evolution of magnetic stresses with in the NS crust, have allowed to relate the observed magnetar phenomenology to the physical properties of the NSs, and in particular to their age and magnetic field strength and topology. The dichotomy of 'high-B' field pulsars versus magnetars is naturally explained, and occasional outbursts from old, low B-field NSs are predicted.
Video
Abstract
This workshop will provide a forum for discussion of the likely astronomical landscape in the 2020s - both core science and burning topics, in so far as these can ever be predicted. Flowing from that, the community is invited to advise the ESO Executive with regard to future facilities, including but not limited to those at the optical/infrared observatories on La Silla and Paranal in Chile, at the sub-millimetre observatories APEX and ALMA on Chajnantor and the Extremely Large Telescope on Armazones.
In addition to high-level summaries there will be ample time for discussion and the presentation of new ideas to shape the future of ESO.
Abstract
Andrea Accomazzo will tackle the operational part i.e. how they got to the comet, how they managed to orbit it, and finally land.
Mark McCaughrean will give an overview of the scientific objectives and findings so far.
Abstract
There is observational evidence that the environment of star forming
regions can significantly affect the evolution of protostellar and
protoplanetary discs. When stars form in groups, EUV (Extreme
Ultraviolet) and FUV (Far Ultraviolet) radiation permeate the young
association, interact with the gas of the disc, and can drive a
gaseous flow from the disc’s edge. Whereas it is well known that
strong FUV backgrounds drive vigorous photoevaporation (as in the
Orion proplyds) it is usually assumed that the effect of the weak FUV
background fields found in nearby star-forming regions have a
negligible effect on disc evolution. We have built a new 1D model in
order to find the radial steady-state structure of the gaseous wind
flowing from accretion discs in both strong and weak FUV fields. Our
results reveal that discs are subject to strong flows even in the
presence of weak background fields (G0 ∼ 30 Draines) if they extend to
radii > 100 AU. This implies a natural mechanism for limiting the
radial spreading of protoplanetary discs, and therefore constrains the
planet-formation potential in their outer regions (where most of the
mass lies). This could be significant for the majority of planetary
systems, since the threshold FUV field is so low. In cluster
environments, the other fundamental phenomenon in the evolution of
protoplanetary discs is tidal interactions. We will present a detailed
model of the RW Aur system. By performing 3D hydro simulations and
producing synthetic observations, we will show that this peculiar
object is very likely undergoing a tidal encounter caused be the
secondary star. RW Aur is the only known good candidate undergoing
such mechanism on the scale of protoplanetary discs. It could thus be
a key system to help constrain this important phenomenon.
Abstract
The appearance of the first stars about 100 million years after the Big Bang marked the beginning of the Reionization Epoch, an extended process in which the cosmic gas was ionized by the UV photons from the existing luminous sources. Most likely, in addition to stars, black holes also formed during the same epoch as end-products of massive star evolution, from direct collapse of gas clouds, or by stellar merging in dense stellar clusters. These black holes represent the "seeds" out of which observed super-massive black holes powering the most distant quasars were built. I will review the properties of first stars and black holes, their role for reionization, and the tight physical relationships between these two types of sources. I will put particular emphasis on the critical current and future experiments that could allow us to understand in detail these initial phases of cosmic structure formation.
Video
Abstract
Supersymmetry is one of the most interesting theories beyond the Standard Model, solving the hierarchy problem and providing an explanation for Dark Matter. Both the ATLAS and the CMS collaborations pursued a rich search programme to discover Supersymmetry during Run 1 of the Large Hadron Collider. Stringent limits were placed in some specific supersymmetric models, e.g. excluding gluino masses below ~1.3 TeV under certain assumptions. Other models remained inaccessible during Run 1 or have not been addressed yet. The increased centre-of-mass energy and statistics in Run 2 will allow to extend the sensitivity of current and novel searches for Supersymmetry considerably. The search for Supersymmetry will thus be one of the main priorities for LHC Run 2. This talk will present a summary of the experimental search strategy for Supersymmetry during Run 1 along with some highlighted results and will present prospects for Run 2.
Abstract
One of the key sites to search for new complex organic molecules in the interstellar medium (ISM) has turned out to be the star-forming, hot, molecular cloud core Sgr B2(N). I will present the first results of the EMoCA survey conducted toward this source with ALMA in its Cycles 0 and 1. This spectral line survey covers the 3 mm atmospheric window and aims at deciphering the molecular content of Sgr B2(N) in order to test the predictions of state-of-the-art astrochemical numerical simulations and to gain insight into the chemical processes at work in the ISM. I will report on the first detection of a branched alkyl molecule in the ISM. I will discuss the implications of this detection in terms of interstellar chemistry and its possible connection to the complex organic molecules found in meteorites.
Abstract
Deep color-magnitude diagrams reaching the oldest main
sequence turnoffs offer the possibility to derive reliable, precise
star formation histories, and even, chemical enrichment histories for
the galaxies in our Local Group. I will discuss these results for a
variety or Local Group galaxies, as well as their implications in a
number of astrophysics topics such as i) the early conditions of the
Universe: reionization and feedback; ii) the dwarf galaxy
classification and the origin of the different dwarf galaxy types;
iii) the effects in interactions in the evolution of the galaxies.
Video
Abstract
Several independent analyses of the Fermi-LAT data observed an excess of gamma rays peaking at 1-3 GeV towards the galactic centre. The origin of this excess is unknown and several explanations in terms of conventional astrophysics, but also dark matter annihilations have been put forward. Assuming its explanation in terms of dark matter annihilations, Michael will discuss how it can be explained within a natural region of parameter space in the Next-to-Minimal Supersymmetric Standard Model (NMSSM).
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