Dr. Sameer

The diffuse gas surrounding galaxies, called the circumgalactic medium (CGM), is a gas reservoir facilitating the growth and evolution of galaxies. While absorption studies offer the most effective approach to investigating the CGM, traditional quasar absorption-line techniques face a fundamental limitation: they typically probe only a single sightline through a galaxy’s halo, yielding an incomplete view of the galaxy's halo. In this talk, I will present an absorption line investigation of the CGM of our nearest galaxy neighbor, the Andromeda Galaxy (M31). With current UV capabilities, M31 is the only single galaxy where we can study the global distribution and properties of metals and baryons in great detail across its entire halo. Using absorption spectroscopy acquired by HST/COS, coupled with photoionization modeling, we place constraints on the physicochemical properties of M31's CGM probed using several tens of sightlines, yielding valuable insights into the CGM-galaxy connection.