Astrophysics Seminar: Dr. Sameer, University of Oklahoma

Starlight and nebular emission lines reveal the baryonic content within galaxies. However, galaxies are embedded in an invisible baryonic reservoir—the circumgalactic medium (CGM)—which comprises most of the universe's baryonic mass and serves as the critical interface between galaxies and the intergalactic medium, mediating galactic growth and evolution. In this talk, I will present our efforts to understand the CGM across cosmic time through metal absorption line spectroscopy. I will begin with new results on the physical conditions, density and temperature distribution in the CGM of Andromeda (M31) at z ∼ 0. Next, I will discuss the galaxy-CGM connection at low redshift (0 < z < 1), where we investigate whether galaxy properties drive observable bimodalities in CGM metallicity and the origins of warm-hot gas traced by O VI. I will then present efforts to characterize the CGM at high redshift (2 < z < 3) using integral field spectroscopy. Finally, I will discuss how cosmological simulations and forward-modeling techniques can help improve our understanding of the multiphase CGM across cosmic history.