C. J. Short, P. A. Thomas, O. E. Young
We present numerical simulations of galaxy clusters with anisotropic heating
from active galactic nuclei (AGN) that are able, for the first time, to
reproduce the observed entropy and temperature profiles of both non-cool-core
(NCC) and cool-core (CC) clusters.
Our study uses N-body hydrodynamical simulations to investigate how star
formation, metal production, black hole accretion, and the associated feedback
from supernovae and AGN, heat and enrich diffuse gas in galaxy clusters. We
assess how different implementations of these processes affect the thermal and
chemical properties of the intracluster medium (ICM), using high-quality X-ray
observations of local clusters to constrain our models. For the purposes of
this study we have resimulated a sample of 25 massive galaxy clusters extracted
from the Millennium Simulation. Sub-grid physics is handled using a
semi-analytic model of galaxy formation, thus guaranteeing that the source of
feedback in our simulations is a population of galaxies with realistic
properties. We find that supernova feedback has no effect on the entropy and
metallicity structure of the ICM, regardless of the method used to inject
energy and metals into the diffuse gas. By including AGN feedback, we are able
to explain the observed entropy and metallicity profiles of clusters, as well
as the X-ray luminosity-temperature scaling relation for NCC systems. A
physical model of AGN energy injection based on anisotropic jet heating -
presented for the first time here - is crucial for this success. With the
addition of metal-dependent radiative cooling, our model is also able to
produce CC clusters, without over-cooling of gas in dense, central regions.
View original:
http://arxiv.org/abs/1201.1104
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