Published in Physics Reports, Volume 427, Issue 1, p. 1-39, 2006.
astro-ph/0512549

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X-RAY SPECTROSCOPY OF COOLING CLUSTERS

J. R. Peterson 1 & A. C. Fabian 2


1 Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), Stanford University, PO Box 20450, Stanford, CA 94309, USA
2 Institute of Astronomy (IoA), Cambridge University, Madingley Road, Cambridge CB3 0HA, UK


Abstract: We review the X-ray spectra of the cores of clusters of galaxies. Recent high resolution X-ray spectroscopic observations have demonstrated a severe deficit of emission at the lowest X-ray temperatures as compared to that expected from simple radiative cooling models. The same observations have provided compelling evidence that the gas in the cores is cooling below half the maximum temperature. We review these results, discuss physical models of cooling clusters, and describe the X-ray instrumentation and analysis techniques used to make these observations. We discuss several viable mechanisms designed to cancel or distort the expected process of X-ray cluster cooling.


Table of Contents

INTRODUCTION

CLUSTERS OF GALAXIES

PHYSICS OF THE INTRACLUSTER MEDIUM
X-ray Emission from Collisional Plasmas
Magneto-hydrodynamics
Cooling flows

X-RAY INSTRUMENTATION AND OBSERVATIONAL TECHNIQUES
X-ray Telescopes and their Relevance to Clusters
Analysis Techniques

X-RAY SPECTRA OF COOLING CLUSTERS
Early Work on Imaging Observations
Early Work on Low Resolution Spectroscopy
Focal Plane Crystal Spectrometer
Reflection Grating Spectrometer Observations
Recent Spatially-resolved Spectro-photometric Observations
Observations of Cataclysmic Variables
Definition of the Cooling Flow Problem

ARE COOLING FLOWS RULED OUT?
Cooled gas and star formation

HEATING
Heat conduction
Heating by a central radio source
Is the ICM turbulent?
Multiphase flows
Role of Magnetic Fields and Cosmic Rays
Feedback
Other heat sources and mechanisms

DISCUSSIONS

FUTURE WORK

REFERENCES

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