Published in "Gas Accretion onto Galaxies", Astrophysics and Space Science Library, Volume 430. ISBN 978-3-319-52511-2. Springer International Publishing AG, 2017, p. 15.
https://arxiv.org/abs/1612.00449

For a PDF version of the article, click here.

GAS ACCRETION ONTO THE MILKY WAY

Philipp Richter


Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Golm, Germany


Abstract: The Milky Way is surrounded by large amounts of gaseous matter that are slowly being accreted over cosmic timescales to support star formation in the disk. The corresponding gas-accretion rate represents a key parameter for the past, present, and future evolution of the Milky Way. In this chapter, we discuss our current understanding of gas accretion processes in the Galaxy by reviewing past and recent observational and theoretical studies. The first part of this review deals with the spatial distribution of the different gas phases in the Milky Way halo, the origin of the gas, and its total mass. The second part discusses the gas dynamics and the physical processes that regulate the gas flow from the outer Galactic halo to the disk. From the most recent studies follows that the present-day gas accretion rate of the Milky Way is a few solar masses per year, which is sufficient to maintain the Galaxy's star-formation rate at its current level.


Table of Contents

INTRODUCTION
Historical remarks
Cosmological context
Parameterization of gas accretion

THE OBSERVED DISTRIBUTION OF GAS AROUND THE MILKY WAY
Neutral gas
IVCs
HVCs
Warm ionized gas
Hot ionized gas
Gas-accretion rates from observations

SIMULATIONS OF MILKY WAY GAS ACCRETION
Hydrodynamical simulations of gas infall
Cosmological hydrodynamical simulations
Comparison with observations

CONCLUDING REMARKS

REFERENCES

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