Seminars and Colloquia at ESO Garching and on the campus

Weak gravitational lensing, the deflection of light from distant galaxies due to all intervening mass along the line of sight, is one of the most direct ways to observe dark matter. As a result, in the past decade, weak lensing has become a very important tool both for constraining cosmological parameters and for revealing the connection between galaxies and dark matter. I will begin by reviewing some recent, significant observational advances related to both galaxies and cosmology that were made possible by weak lensing. Next, I will outline some of the challenges and opportunities facing the lensing community in existing and upcoming imaging surveys. I will conclude with some perspective on how these challenges will be addressed to do ground-breaking work in the fields of cosmology, galaxy formation, and galaxy cluster formation and evolution with weak lensing observations in the next decade.

Supermassive black holes pass through several 'ages' - birth, rapid growth at high redshift, moderate growth as quasars, merger growth, and slow growth as radio galaxies and Seyferts, and finally a turn-off. Downsizing of active black holes toward the present means that turned off quasars remain quiescent, a kind of "quasar death". Most of this life cycle is very poorly known, with only the quasar phase well studied. I will describe our new studies, based on both the COSMOS and the SDSS DR5 quasar samples, which shed light on this quasar death phase, as well as adding new complexity to the quasar and merger growth phases. These studies include a careful examination of the Mass-Luminosity plane for quasars, and the nature of 'intrinsically red' quasars based on joint optical and X-ray observations.

Studying ultraluminous galaxies (ULIRGs) at early times (z>2) provides insight into the formative phases of massive galaxies around us today. While the filed has become a relatively mature science, there remain various aspects of this field that are still mired in uncertainty, and new facilities offer possibilities for great leaps forward in our understanding. I will provide an overview of this exciting field, and present new avenues of research into high-z ULIRGs which are significantly pushing our understanding of the population. These include Herschel-HerMES, the South Pole Telescope (SPT), our recently completed IRAM-PdBI survey of CO 50 high-z SMGs (Bothwell et al. 2011), and the CDFS-LESS survey with LABOCA and its followup.

What has been the most profound discovery, progress or idea that has emerged in astronomy over the last decade? And what will be the most important challenge in astronomical research in the next decade? These questions are at the heart of our discipline, but we rarely venture outside of our own niche areas. I will attempt to focus on the broad picture underlying the field of star formation and discuss the requisite conditions for sustained progress in this field, aided by recent achievements in the context of my group's star cluster research.

Planetary nebulae reflect the death throes of Sun-like stars. During their final phase of nuclear burning, between 20% and 80% of the mass of the star is ejected through a 'super'-wind. The ejection processdetermines the white dwarf mass distribution, and is the origin of up to half of the gas and dust in the ISM. The cause, evolution and composition of this catastrophic mass loss is still a matter of debate. Observations of planetary nebulae and their progeny, AGB stars, provide important constraints on the superwind and its origin. This talk will discuss mass loss in RGB and AGB stars, including the fate of iron, the formation process of PAHs, and the formation and destruction of dust disks. Observations of planetary nebulae in the Galactic Bulge provide surprising results on the binary stellar population of the Galactic Bulge.