Simulations of AGN Feedback in Galaxy Clusters and Groups: Impact on Gas Fractions and the L _X - T Scaling Relation

Abstract

Recently, rapid observational and theoretical progress has established that black holes (BHs) play a decisive role in the formation and evolution of individual galaxies as well as galaxy groups and clusters. In particular, there is compelling evidence that BHs vigorously interact with their surroundings in the central regions of galaxy clusters, indicating that any realistic model of cluster formation needs to account for these processes. This is also suggested by the failure of previous generations of hydrodynamical simulations without BH physics to simultaneously account for the paucity of strong cooling flows in clusters, the slope and amplitude of the observed cluster scaling relations, and the high-luminosity cutoff of central cluster galaxies. Here we use high-resolution cosmological simulations of a large cluster and group sample to study how BHs affect their host systems. We focus on two specific properties, the halo gas fraction and the X-ray luminosity-temperature scaling relation, both of which are notoriously difficult to reproduce in self-consistent hydrodynamical simulations. We show that BH feedback can solve both of these issues, bringing them in excellent agreement with observations, without alluding to the "cooling only" solution that produces unphysically bright central galaxies. By comparing a large sample of simulated AGN-heated clusters with observations, our new simulation technique should make it possible to reliably calibrate observational biases in cluster surveys, thereby enabling various high-precision cosmological studies of the dark matter and dark energy content of the universe.

Scaling Relations for Galaxy Clusters: Properties and Evolution

“…Sijacki & Springel (2006) developed a model for AGN heating via hot thermal bubbles in a cosmological simulation of cluster formation. Puchwein et al (2008) have shown that the observed L X − T relation is successfully reproduced without invoking excessive cooling in the central region of the simulated clusters. However this model does fail to reproduce the observed entropy profiles.…”

Rhapsody-G simulations – II. Baryonic growth and metal enrichment in massive galaxy clusters

“…Most state-of-the-art cosmological zoom-in simulations of galaxy clusters reach a spatial resolution of "kpc (Puchwein et al 2008;Teyssier et al 2011;Ettori et al 2012;Martizzi et al 2014b;Le Brun et al 2014;Lau et al 2015;Sembolini et al 2015). Such simulations are challenging since they require a very large dynamic range of scales to be captured: from the scales at which galaxies assemble their stars to the scale at which cosmological gas accretion onto clusters happens.…”

TheLX – Tvirrelation in galaxy clusters: effects of radiative cooling and AGN heating

“…Several works, based on both observations and simulations, have indicated that the L X −T vir relation in low-mass halos with a central radio source differs systematically from that in systems without a central radio source Croston et al 2005;Puchwein et al 2008). Studies also show that clusters with strong cooling, as indicated by either the short cooling times of the intracluster gas or high classical gas mass deposition rates, lie on a different L X −T vir plane (e.g., Allen & Fabian 1998;O'Hara et al 2006).…”