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Title: Galaxy-wide outflows: cold gas and star formation at high speeds
Authors: Zubovas, K.
King, Andrew Robert
First Published: 30-Jan-2014
Publisher: Oxford University Press (OUP)
Citation: Monthly Notices Of The Royal Astronomical Society, 2014, 439 (1), pp. 400-406 (7)
Abstract: Several active galaxies show strong evidence for fast (v[Subscript: out] ∼ 1000 km s[Superscript: −1]) massive (M˙=M˙= several × 1000 M[Subscript: ⊙] yr[Superscript: −1]) gas outflows. Such outflows are expected on theoretical grounds once the central supermassive black hole reaches the mass set by the M-σ relation, and may be what makes galaxies become red and dead. Despite their high velocities, which imply temperatures far above those necessary for molecule dissociation, the outflows contain large amounts of molecular gas. To understand this surprising result, we investigate the gas cooling and show that the outflows cannot stably persist in high-temperature states. Instead, the outflowing gas forms a two-phase medium, with cold dense molecular clumps mixed with hot tenuous gas, as observed. We also show that efficient cooling leads to star formation, providing an observable outflow signature. The central parts of the outflows can be intrinsically luminous gamma-ray sources, provided that the central black hole is still strongly accreting. We note also that these outflows can persist for ∼108 yr after the central AGN has turned off, so that many observed outflows (particularly with high speeds) otherwise assumed to be driven by starbursts might also be of this type.
DOI Link: 10.1093/mnras/stt2472
ISSN: 0035-8711
eISSN: 1365-2966
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2014The Author. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Deposited with reference to the publisher’s archiving policy available on the SHERPA/RoMEO website.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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