Annu. Rev. Astron. Astrophys. 2003. 41: 191-239
Copyright © 2003 by . All rights reserved

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HOT GAS IN AND AROUND ELLIPTICAL GALAXIES

William G. Mathews 1 and Fabrizio Brighenti 1, 2


1 University of California Observatories/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 mathews@ucolick.org
2 Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, Bologna 40127, Italy brighenti@bo.astro.it


Abstract. We review the origin, evolution and physical nature of hot gas in elliptical galaxies and associated galaxy groups. Unanticipated recent X-ray observations with Chandra and XMM indicate much less cooling than previously expected. Consequently, many long-held assumptions need to be reexamined or discarded and new approaches must be explored. Chief among these are the role of heating by active galactic nuclei, the influence of radio lobes on the hot gas, details of the cooling process, possible relation between the hot and colder gas in elliptical galaxies, and the complexities of stellar enrichment of the hot gas.


Keywords elliptical galaxies, X-rays, cooling flows, galaxy groups, galaxy clusters


Table of Contents

INTRODUCTION

OVERVIEW OF HOT GAS FLOWS IN AND NEAR ELLIPTICAL GALAXIES

BASIC PROPERTIES OF ELLIPTICAL GALAXIES AND THEIR HOT GAS

HYDROSTATIC EQUILIBRIUM AND MASS DETERMINATIONS

GAS DYNAMICAL EQUATIONS AND CLASSIC COOLING FLOWS

SIMPLE COOLING FLOW MODELS

THE COOLING PARADOX - DOES THE GAS COOL?
Spectroscopic and Morphological Cooling Rates
Warm and Cold Gas at T < 105 K
Dust in Elliptical Galaxies
Origin of Warm Gas, Cold Gas and Dust
Hiding the Cooling Gas

COOLING FLOWS HEATED BY ACTIVE NUCLEI
Chandra Observations and Entropy Floors
AGN Heating
Cooling Flow Models with Heating
Models of X-ray Cavities

ROTATION AND MAGNETIC FIELDS

ABUNDANCES IN THE HOT GAS

REFERENCES

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