Publication Date

2001

Journal or Book Title

Tracing Cosmic Evolution with Galaxy Clusters

Abstract

We investigate the X-ray vs. optical scaling relations of poor groups
to small clusters (  100−700 km/s) identified in a cosmological hydro-
dynamic simulation of a ΛCDM universe, with cooling and star forma-
tion but no pre-heating. We find that the scaling relations between X-ray
luminosity, X-ray temperature, and velocity dispersion show significant
departures from the relations predicted by simple hydrostatic equilibrium
models or simulations without cooling, having steeper LX− and LX−TX
slopes and a “break” at  200 km/s ( 0.3 keV). These departures arise
because the hot (X-ray emitting) gas fraction varies substantially with
halo mass in this regime. Our predictions roughly agree with observa-
tions. Thus radiative cooling is a critical physical process in modeling
galaxy groups, and may present an alternative to ad hoc models such as
pre-heating or entropy floors for explaining X-ray group scaling relations.

Comments

This is the pre-published version harvested from ArXiv. The published version is located at http://www.aspbooks.org/a/volumes/article_details/?paper_id=24994

Volume

268

Pages

236

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