Galactic Atmospheres

By (author) G. Mark Voit

Publication date:

Q4 2025

Length of book:

500 pages

Publisher

Institute Of Physics Publishing

Dimensions:

254x178mm
7x10"

ISBN-13: 9780750348492

BOOK DESCRIPTION
TABLE OF CONTENTS

Observational progress on numerous fronts, particularly with the Cosmic Origins Spectrograph on the Hubble Space Telescope, have revealed that most of the gas associated with a galaxy lies outside of it, in its atmosphere and have also shown that what happens inside a galaxy is closely connected to what is happening in its atmosphere. Driven by these findings, astronomers are increasingly reconsidering the critical role of galactic atmospheres in regulating galaxy evolution. This book will present a unique perspective on galaxies and how they evolve, motivated by these recent findings about the surrounding gas. It will show how atmospheres around all galaxies, from small dwarf galaxies to the giant galaxies at the centers of galaxy clusters, respond to a common set of physical principles. Its focus will be on building physical intuition about how galaxies function as self-regulating systems, emphasizing how feedback powered by supernova explosions and gas accretion onto supermassive black holes shapes the populations of stars within galaxies. And it will conclude by pointing forward into the near future, anticipating what astronomers may soon learn about galactic atmospheres from coming advances in observational capabilities.

Key Features:

Written by a world leading expert in the field

Gives a unique synthesis of the atmospheric properties of galaxies, going from dwarf galaxies all the way up to the universe’s biggest galaxies

Provides a pedagogical approach that builds upon concepts from undergraduate physics and connects them with current research topics

Suitable for supporting graduate courses that include galaxy evolution

1 - Overview of Galaxy Formation
Qualitative outline of how galaxies are thought to form and evolve, to provide context for
the ensuing discussion of galactic atmospheres and to communicate expectations about
background knowledge.
2 - Cosmological Halos
Basic quantitative outline of cosmological structure formation, presenting the properties
of the halos that confine galactic atmospheres.
3 - Observations of Atmospheres
An overview of current observational constraints on the atmospheres of galaxies.
4 - Atmospheric Accretion
A closer look at how gas accretes into cosmological halos and passes through accretion
shocks, thereby generating the entropy that determines the properties of galactic
atmospheres.
5 - Radiative Cooling
Radiative energy losses allow galaxy formation to happen at the center of a galactic
atmosphere. This chapter shows how those losses depend on halo mass and chemical
enrichment of the atmosphere.
6 - Supernova Feedback
The central galaxy of a halo responds to cooling and star formation with outbursts of
energy from supernova explosions. This chapter assesses how supernova energy and the
galactic winds that supernovae drive affect the properties of galactic atmospheres.
7 - Black Hole Feedback
Atmospheres around the universe’s most massive galaxies are more strongly affected by
outflows powered by black-hole accretion than by outflows powered by supernovae. This
chapter assesses how outflows driven by black holes affect the properties of galactic
atmospheres.
8 - Thermal Stability
Galactic atmospheres often contain gas that differs greatly in temperature and density.
This chapter analyses the conditions that determine whether such an atmosphere
develops such structure through thermal instability leading to multiphase condensation.
9 - Self-Regulation
The atmospheres of massive galaxies exhibit similarities indicating that feedback maintains
them in a quasi-steady state, implying that feedback is self-regulating. This chapter
explores the phenomena capable of closing the feedback loop, including the possibility of
a tight link between thermal stability and triggering of feedback.
10 - Angular Momentum
Lower mass galaxies frequently contain gaseous disks, implying the presence of angular
momentum in the gas supply from the atmosphere. This chapter considers how angular
momentum alters the nature of thermal stability and self-regulation via feedback.
11 - Atmospheres & Star Formation
A galaxy’s ability to form stars depends on how effectively feedback regulates cooling and
condensation of its atmosphere. This chapter shows how a galaxy’s star formation rate
relates to conditions in its atmosphere.
12 - Observational Frontiers
Advances in observational capabilities during the next couple of decades will greatly
expand the ability of astronomers to explore gas around galaxies that was previously
invisible. This chapter concludes the book by surveying the techniques that will be used to
address many questions that currently remain open.