Seminars and Colloquia at ESO Garching and on the campus

Despite the crucial role that massive stars have in the evolution of their host galaxies, the processes and the stages that lead to their formation are not yet completely understood. One of the biggest uncertainties comes from the lack of a solid diagnostic tool to classify massive young stellar objects (MYSOs) according to their evolutionary stage. Currently, the only evolutionary indicator for MYSOs is L/M (bolometric luminosity to envelope-mass ratio), based on a theoretical classification scheme from the low-mass SF model. However, this method is severely hampered by the extreme extinction of high-mass star forming sites and by the poor resolution of existing facilities in the infrared (IR) regime which limits the accessible scales to those of entire proto-clusters. My PhD project proposes a novel approach to investigate the mid-IR properties of single members of proto-clusters using several transitions of different molecules sensitive to the radiation field of MYSOs through ALMA observations. In this presentation, I will show the novel method proposed and the analysis on a pilot sample of well known and characterised massive proto-clusters in different evolutionary phases.

Nowadays it is possible to observe planet forming environment with incredibly high spatial and spectral resolution thanks to ALMA telescope. Recently, protoplanetary disc kinematics gained a lot of interest, as it directly probes disc structure, unveils planet disc interaction and tests the presence of hydrodynamical instabilities.

exoALMA is an ALMA large program, whose aim is to characterise the kinematics of protoplanetary environments with unprecedented spatial and spectral resolution. In this talk I will present my work within exoALMA collaboration, which involves modelling the rotation curves to constrain fundamental properties such as disc mass, stellar mass and scale radius. The knowledge of such quantities allows to investigate disc composition, to compare with thermochemical models and to constrain the efficiency of angular momentum transport.

The most underdense regions of the Universe are the home of a population of gas-rich and low-metallicity dwarf galaxies. These galaxies could be the key to understand the earlier stages of hierarchical assembly within the ΛCDM. These galaxies present the exciting puzzle of how their stellar masses assembled — through gas accretion from the IGM, mergers, or a combination of both? The few observational and theoretical studies dedicated to this topic show conflicting results; during this discussion, I will outline an ongoing project that aims to address these questions by analyzing their neutral gas content and metallicity gradients, providing new insights into the assembly history of these galaxies.

Over the past 15 years, the Atacama Large Millimeter/submillimeter Array (ALMA) in the Chilean desert has revolutionized our understanding of planetary formation. ALMA has not only provided the expected large samples and high-resolution images of planet-forming material, but it has also led to groundbreaking discoveries that challenge existing theories. One of the most striking revelations is that planets form much faster than previously thought. In this talk, I will explore the key concepts and scales involved in the process of building planets from micrometer-sized cosmic dust. I will discuss how theory and observations help us reimagine how planetary systems, both similar and very different from our own, are formed. 

Precise knowledge of focal plane point spread function (PSF) is essential in many scientific data post-processing applications, including deconvolution, as well as precise astrometry and photometry. Moreover, as the culmination of the imaging process, PSF “absorbs” the cumulative effect of all contributors along the optical path, thus encoding valuable information about the optical system that can be utilized for diagnostics and calibration.

In this talk, I will introduce two PSF-based techniques for adaptive optics (AO) system calibration and scientific data post-processing.

The first part will focus on a method for retrieving quasi-static aberrations from focal-plane PSFs. The approach was tested on-sky using the low-order wavefront sensor of the MUSE Narrow-Field Mode (NFM). The results demonstrated the ability of the method to measure non-common path aberrations effectively under real observing conditions.

The second part will introduce a technique for realistic modeling of AO-corrected science PSFs using reduced AO telemetry and atmospheric monitoring data. The method was validated with on-sky data from the MUSE NFM and SPHERE IRDIS instruments, achieving small discrepancies between the predicted and observed PSFs. In addition, the proposed technique demonstrated the ability to accurately predict the wavefront errors induced by the low-wind effect based solely on reduced AO telemetry and atmospheric data.

The evolution of galaxy clusters is highly influenced by the dynamics of the Intracluster Medium (ICM), which governs crucial mechanisms. This includes mixing, turbulence processes, and galaxy interactions within the cluster environment. Among the factors influencing the ICM dynamics, the impact of viscosity is still under debate. Understanding the effect of viscosity on the evolution of galaxy clusters is fundamental for comprehending gas properties and the underlying dynamics within the ICM.

By conducting a thorough study, we aim to highlight the implications that viscosity introduces compared to inviscid simulations. These implications encompass morphological differences, larger density fluctuations, and the intricate interplay of the magnetic field amplification, among other fundamental effects. Our results challenge prior assumptions, especially concerning the constraints on viscosity within the ICM. This study is expected to enhance our understanding of ICM dynamics and contribute to our knowledge of galaxy cluster evolution.