Satellite galaxies and the baryon cycle

Abstract: Late-time galaxy evolution is driven by a variety of non-linear processes such as radiative cooling, supernova feedback and AGN accretion, which together act to largely decouple baryonic structure growth from that of the dark matter.  It remains a formidable challenge to untangle these processes using theoretical or simulation techniques, necessitating an empirical approach through controlled observations.  One way to attempt this is by comparing the properties of satellite galaxies to those of galaxies that are central, or dominant, in their host halo.  As much of the physics on kiloparsec scales and smaller is likely the same, the comparison in principle enables a useful test of models by controlling for many uncertain parameters.  I will present recent and forthcoming observations of galaxy clusters and groups at 0.8<z<1.5 in this context.  We find tantalizing suggestions that the differential evolution of satellite galaxies at these redshifts is driven by fundamentally different processes from those, like ram pressure stripping, that drive local cluster galaxy evolution.  If our interpretation is correct, it may explain why simulations have had such difficulty reproducing the observed properties of nearby satellite galaxies, with corresponding implications on our understanding of gas ejection rates associated with feedback.

Cody Hall

Michael Balogh, University of Waterloo

January 22, 2016
14:00 - 15:00