Seminars and Colloquia at ESO Garching and on the campus
I will present the results of my master thesis project on quasar feedback and outflows, which have been submitted for publication to MNRAS and announced at https://arxiv.org/abs/1906.00985.
The Active Galactic Nuclei (AGNs) play a major role in the evolution of the galaxies, thanks to their ability to launch powerful outflows. The detection of nuclear X-ray winds, as well as ionised and molecular galactic outflows provide direct evidence of the so called feedback processes in action, whose physics is nevertheless poorly understood.
I have studied a local AGN hosting a powerful nuclear X-ray wind, using ALMA observations in order to trace, at galactic scales, the molecular ISM kinematics. I found the signature of a possible molecular outflow with v~200 km/s that is potentially able to suppress the star-formation activity. By comparing the energetics of this putative outflow with that of the nuclear wind, I tested the blast-wave AGN feedback scenario favouring a momentum-driven outflow over an energy-driven model.
I will introduce the scientific background, present the data analysis and discuss the possible interpretations of the results and their implications.
I will present results from a catalog of ~1.8 million Omega Cen member stars derived from DECam photometry covering a field of view of ~5x5 degrees across the cluster and HST data for the innermost regions. The unprecedented accuracy of DECam photometry, the depth and field coverage, combined with HST data for the cluster core, allowed me for the first time to derive the global stellar density profile of Omega Cen based on star counts of red-giant and main-sequence stars from 1 to ~140 arcminutes.
The King and Wilson models fail to reproduce the outermost shape of Omega Cen density profile suggesting that the interaction with the Galactic tidal field and the presence of potential escaper (extra-tidal) stars need to be taken into account to explain the observations. The best fit of Omega Cen density profile is found with the SPES models which include potential escaper stars, confirming the presence of a stellar halo around the cluster.
In the last decade we have explored the cosmic depths and found a statistically significant number of galaxies well into the Epoch of Reionization. However, our physical knowledge of these pristine objects remains very scant. Investigating the internal structure, interstellar medium and evolution of early galaxies is the next challenge to understand key processes as the cosmic history of baryons, feedback, reionization and metal enrichment of the intergalactic medium, This ambitious plan can be tackled by combining a new generation of physically-rich, high resolution, zoom simulations with data in the sub-mm bands provided by ALMA. This approach will be soon strengthened by the forthcoming JWST power. I will review the present status and the open questions in the field.