The Evolution and Quenching of Galaxies after z ~ 3

I will describe a toy power-law model for the growth of black holes ingalaxies and their role in quenching.  Galaxies while star-forming areassumed to exist at the centers of relatively undisturbed dark halos,and their stellar masses and radii Re are linked to their haloproperties via simple power-law relations.  Black hole mass is assumedto correlate with central stellar density, which implies a connectionto halo properties via the previous assumptions.  Quenching occurswhen the total energy emitted by the black hole, Ebh, equals sometotal energy needed to heat the halo, Ehalo, which is assumed to behave the functional form f(z) Mvir^t, where f(z) is a function ofredshift.  The functional form of f(z) and the value of t are derivedby fitting to the observed distribution of star-forming galaxies inthe R_e - M* plane and the ridgeline of quenched galaxies in the Sig1- M* plane from z ~ 3 to now.  It is further shown that theempirically derived from for Ehalo is virtually to the thermal energycontent of the hot gas in the halo as a function of time.  Theimplications are that 1) halos are a 2-parameter family that imprinttheir properties on the M* and Re of galaxies, 2) halos "know" abouttheir BH masses because the two are connected through the propertiesof their central galaxy, and 3) galaxies quench when the energydeposited by their BHs approximately doubles the thermal energy intheir hot-gas halos. 

Sandra M. Faber
University of California Santa Cruz
KIAA-PKU Auditorium
Luis Ho
Wednesday, September 19, 2018 - 4:00pm to 5:00pm