Speaker (online): Pritom Mozumdar, Postdoctoral Researcher, Department of Physics and Astronomy, University of California, Los Angeles, USA.
Title: Probing galaxy evolution using massive early-type galaxies at intermediate redshift
Abstract: Over the past 8 billion years (since redshift, z ~ 1), the Universe – and the galaxies within it – have changed dramatically. Cosmological simulations suggest that massive early-type galaxies (ETGs), which are large, old systems mostly made of stars, have slowly transformed in their internal structure during this time. However, observational evidence of these transformations at intermediate redshift ( z ~ 0.5) isn’t conclusive and sometimes even seems to disagree with what simulations predict. One major reason is the lack of statistically large sample of ETGs with high-quality data at intermediate redshifts. To fill this gap, I assembled a sample of around 200 massive ETGs at 0.25 < z < 0.75. With this dataset, I addressed two big questions – 1) Have the stars in these galaxies become more randomly moving, that is, have their motions become less ordered, over cosmic time? 2) Has the overall distribution of mass, including both stars and dark matter, changed as the Universe aged? By comparing these galaxies to similar ones in today’s Universe (z ~ 0), I found evidence that both the stellar motions and the mass distributions have evolved – offering new clues about how massive galaxies grew and changed over cosmic history.
