Beecroft Institute for Particle Astrophysics and Cosmology

Abstract:

There is growing interest in the possible link between the growth of supermassive black holes and the effect of feedback from them on galaxy growth. There are three areas of significant uncertainty: (i) the physics of the feedback; (ii) the prevalence and effectiveness of feedback; (iii) the link between the growth of black holes and their hosts. The 2QZ optical QSO survey indicates that luminous QSOs are relatively short-lived, and it has recently been shown that the observed bolometric luminosity density from all AGN and its evolution can be reproduced if black holes grew coevally with their galaxies, implying but not requiring a causal link between galaxy growth and black hole growth. At low redshifts there is some evidence that black hole and galaxy growth are starting to decouple.

Abstract:

This contribution discusses the challenges of implementing star formation and stellar feedback processes in galaxy simulations. Insufficient computational power and numerous poorly understood physical processes, force simulations to adopt sub-grid models of the interstellar medium. These may crucially bias results. We advocate for smaller (similar to kiloparsec) scale simulations of the interstellar medium to guide the development of sub-grid models in larger simulations. In this vein, I show results on ever increasing scales ranging from similar to 1 h(-1) kpc(3) ISM simulations, to a 1 h(-1) Mpc(3) simulation of a galaxy forming at evolved high redshift, to a larger cosmological volume, 6.25 h(-1) Mpc(3), down to redshift 3. We find that galactic winds can be powered by SN implemented as point explosions in high redshift galaxies simulated with sufficient spatial resolution. Galaxies at lower redshift require alternative sub-grid feedback models and we present one possible solution to generate winds from galaxies at redshift similar to 4.