#StudentSeminar: Astrophysics and Cosmology session

por Ezequiel Albentosa Ruiz, Óscar Monllor Berbegall

miércoles 4 jun. 2025 15:00 → 16:30 Europe/Madrid

Faculty of Physics. Room 4112 (Building D, first floor) (Campus Burjassot)

15:00 - Óscar Monllor Berbegall

Galaxy formation and evolution in a cosmological context

Abstract:
One of the central challenges in modern astrophysics is understanding the mechanisms that drive the formation and evolution of galaxies, as observed both in the present day and throughout the history of the Universe. With the advent of the James Webb Space Telescope (JWST), even processes once considered well-understood are being re-evaluated in light of new and surprising observations.

Galaxy evolution is shaped by a combination of large-scale dark matter dynamics and small-scale baryonic processes, such as gas dynamics, cooling, star formation, stellar feedback, and activity from active galactic nuclei (AGNs), each requiring complex physical modeling. In this way, galaxies act as a bridge between cosmological structures (like clusters, filaments, and voids) and local astrophysical phenomena, making them a key component in the broader cosmological puzzle.

Determining the relative contribution of these processes — whether in individual galaxies or across the galaxy population — remains a significant challenge. As a result, the evolution of galaxies continues to be, in many respects, a profound and open question.

 

15:40h - Ezequiel Albentosa Ruiz

Full-polarization variability of Sgr A* from ALMA

Abstract:
The Galactic Center supermassive black hole, Sagittarius A* (Sgr A*), provides a unique laboratory for studying astrophysical variability across wavelengths. Using high-cadence, full-polarization light curves from ALMA observations during the 2018 Event Horizon Telescope (EHT) campaign (April 21–25), we analyze Sgr A*'s variability and polarization properties with standard time-series analysis tools. Comparing these results with the April 2017 light curves offers insights into the variability and consistency of Sgr A*'s behavior across both observational campaigns.

We also take a closer look at April 24, 2018, when Chandra detected a notable X-ray flare, to investigate the time delay between high-energy and mm-wavelength peaks. Finally, we compare the observed variability in our light curves with predictions from GRMHD simulations, evaluating accretion models near Sgr A* under extreme conditions. The results presented in this talk provide new insights into Sgr A*'s accretion dynamics and multi-wavelength emission.