TY - JOUR
T1 - Fast winds drive slow shells
T2 - A model for the circumgalactic medium as galactic wind-driven bubbles
AU - Lochhaas, Cassandra
AU - Thompson, Todd A.
AU - Quataert, Eliot
AU - Weinberg, David H.
N1 - Funding Information:
The authors thank the anonymous referee for providing helpful suggestions for the improvement of the manuscript. We thank Romeel Davé, Brian A. Keeney, Jessica K. Werk, and Sowgat Muzahid for helpful discussion. CL thanks Adam K. Leroy for interesting ideas for further study. We thank the Simons Foundation for funding the workshop Galactic Winds; Beyond Phenomenology, where aspects of this work were conceived. CL and TAT are supported in part by National Science Foundation Grant #1516967 and NASA ATP 80NSSC18K0526. EQ was supported in part by National Science Foundation Grant AST-1715070 and a Simons Investigator Award from the Simons Foundation.
Publisher Copyright:
© 2018 The Author(s).
PY - 2018/12/1
Y1 - 2018/12/1
N2 - Successful models of the low-redshift circumgalactic medium (CGM) must account for (1) a large amount of gas, (2) relatively slow gas velocities, (3) a high degree of metal enrichment, (4) the similar absorption properties around both star-forming and passive galaxies, and (5) the observationally inferred temperature and densities of the CGM gas.We show that galactic wind-driven bubbles can account for these observed properties.We develop a model describing the motion of bubbles driven by a hot, fast galactic wind characteristic of supernova energy injection. The bubble size grows slowly to hundreds of kiloparsecs over 5-10 Gyr. For high star formation rates or high wind mass-loading M˙w/ M˙*, the free-flowing hot wind, the shocked hot wind in the interior of the bubble, and the swept-up halo gas within the bubble shell can all radiatively cool and contribute to low-ionization state metal line absorption.We verify that if the free-flowing wind cools, the shocked wind does as well. We find effective mass-loading factors of (Mw + Mswept)/M* ~ 5 - 12 as the bubbles sweep into the CGM. We predict cool gas masses, velocities, column densities, metal content, and absorption line velocities and linewidths of the bubble for a range of parameter choices. This picture can reproduce many of the COS-Halos and Keeney et al. (2017) observations of low-ionization state metal absorption lines around both star-forming and passive galaxies.
AB - Successful models of the low-redshift circumgalactic medium (CGM) must account for (1) a large amount of gas, (2) relatively slow gas velocities, (3) a high degree of metal enrichment, (4) the similar absorption properties around both star-forming and passive galaxies, and (5) the observationally inferred temperature and densities of the CGM gas.We show that galactic wind-driven bubbles can account for these observed properties.We develop a model describing the motion of bubbles driven by a hot, fast galactic wind characteristic of supernova energy injection. The bubble size grows slowly to hundreds of kiloparsecs over 5-10 Gyr. For high star formation rates or high wind mass-loading M˙w/ M˙*, the free-flowing hot wind, the shocked hot wind in the interior of the bubble, and the swept-up halo gas within the bubble shell can all radiatively cool and contribute to low-ionization state metal line absorption.We verify that if the free-flowing wind cools, the shocked wind does as well. We find effective mass-loading factors of (Mw + Mswept)/M* ~ 5 - 12 as the bubbles sweep into the CGM. We predict cool gas masses, velocities, column densities, metal content, and absorption line velocities and linewidths of the bubble for a range of parameter choices. This picture can reproduce many of the COS-Halos and Keeney et al. (2017) observations of low-ionization state metal absorption lines around both star-forming and passive galaxies.
KW - Galaxies: general
KW - Galaxies: haloes
KW - Galaxies: starburst
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U2 - 10.1093/MNRAS/STY2421
DO - 10.1093/MNRAS/STY2421
M3 - Article
AN - SCOPUS:85054206611
SN - 0035-8711
VL - 481
SP - 1873
EP - 1896
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -