Orianne Roos - December 4, 2015

AGN and stellar feedback in high-resolution galaxy simulations: how do they
affect star formation?

With high-resolution simulations of star-forming disk galaxies 
at high redshift, we study the effects of combined AGN and stellar 
feedback models on the gas of the host-galaxy. AGN feedback is 
modeled using a standard thermal recipe of feedback (gas is heated 
and pushed away) plus a post-processing method to compute AGN 
ionization. We first consider AGN feedback only and show that, even 
though the AGN generates powerful outflows, the effects of AGN 
feedback on star formation is relatively weak on time-scales up to
 a few 100s of Myrs, even when long-range radiative feedback is 
accounted for. Furthermore, as the combination of stellar feedback 
models generates outflows that are more powerful than the sum of the
 models taken separately, we check whether combined AGN and stellar 
feedback also couple non-linearly. We then include several stellar 
feedback sources on top of AGN feedback, such as young stars creating 
HII regions through radiative pressure and supernovae releasing thermal 
and kinetic energy in the ISM. We follow their impact on the gas of 
high-resolution (1.5 pc) simulations and study the coupling between the 
different sources of outflows (AGN, young stars, supernovae), which 
could produce very fast outflows, with important outflow rates. 
How do these feedback-driven winds affect the host? What is the amount 
of expelled gas? What is its density and temperature and what is the 
consequence for in place and future star formation? Can such outflows 
change the distribution of existing stars?