A Caltech Library Service

How stellar feedback simultaneously regulates star formation and drives outflows

Hayward, Christopher C. and Hopkins, Philip F. (2017) How stellar feedback simultaneously regulates star formation and drives outflows. Monthly Notices of the Royal Astronomical Society, 465 (2). pp. 1682-1698. ISSN 0035-8711. doi:10.1093/mnras/stw2888.

[img] PDF - Published Version
See Usage Policy.

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


We present an analytic model for how momentum deposition from stellar feedback simultaneously regulates star formation and drives outflows in a turbulent interstellar medium (ISM). Because the ISM is turbulent, a given patch of ISM exhibits sub-patches with a range of surface densities. The high-density patches are ‘pushed’ by feedback, thereby driving turbulence and self-regulating local star formation. Sufficiently low-density patches, however, are accelerated to above the escape velocity before the region can self-adjust and are thus vented as outflows. When the gas fraction is ≳ 0.3, the ratio of the turbulent velocity dispersion to the circular velocity is sufficiently high that at any given time, of the order of half of the ISM has surface density less than the critical value and thus can be blown out on a dynamical time. The resulting outflows have a mass-loading factor (η≡M_(out)/M_⋆) that is inversely proportional to the gas fraction times the circular velocity. At low gas fractions, the star formation rate needed for local self-regulation, and corresponding turbulent Mach number, declines rapidly; the ISM is ‘smoother’, and it is actually more difficult to drive winds with large mass-loading factors. Crucially, our model predicts that stellar-feedback-driven outflows should be suppressed at z≲1 in M_⋆≳10^(10)M_⊙ galaxies. This mechanism allows massive galaxies to exhibit violent outflows at high redshifts and then ‘shut down’ those outflows at late times, thereby enabling the formation of a smooth, extended thin stellar disc. We provide simple fitting functions for η that should be useful for sub-resolution and semi-analytic models.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Hayward, Christopher C.0000-0003-4073-3236
Hopkins, Philip F.0000-0003-3729-1684
Additional Information:© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 November 7. Received 2016 November 7; in original form 2015 October 20. We thank Lee Armus, Benham Darvish, Claude-André Faucher-Giguère, Tim Heckman, Andrey Kravtsov, Crystal Martin, Sasha Muratov, Eve Ostriker, Joel Primack, and Rachel Somerville for useful discussions, Sasha Muratov for providing data from Muratov et al. (2015) in electronic form, and Andrey Kravtsov for noting a typo. We also thank the reviewer for a constructive report that helped improve the quality of the manuscript. CCH is grateful to the Gordon and Betty Moore Foundation for financial support, and he is especially grateful to Emmett Hayward for motivating rapid completion of the manuscript by his impending arrival, Tara Hayward for enabling his arrival, and Lori Diebold for facilitating both the completion of the manuscript and the arrival of Emmett. The Flatiron Institute is supported by the Simons Foundation. Support for PFH was provided by an Alfred P. Sloan Research Fellowship, NASA ATP Grant NNX14AH35G, and NSF Collaborative Research Grant 1411920 and CAREER grant 1455342. This work was supported in part by National Science Foundation Grant No. PHYS-1066293 and the hospitality of the Aspen Center for Physics, and it benefitted greatly from CCH's participation in the 2015 ACP Summer Program ‘The Physics of Accretion and Feedback in the Circum-Galactic Medium’, the BIRS-CMO workshop ‘Computing the Universe: At the Intersection of Computer Science and Cosmology’, and the KITP programme ‘The Cold Universe’. This research has made use of NASA's Astrophysics Data System Bibliographic Services.
Group:TAPIR, Astronomy Department
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Simons FoundationUNSPECIFIED
Subject Keywords:methods: analytical, ISM: jets and outflows, galaxies: evolution, galaxies: formation, galaxies: ISM, cosmology: theory
Issue or Number:2
Record Number:CaltechAUTHORS:20160301-105518286
Persistent URL:
Official Citation:Christopher C. Hayward, Philip F. Hopkins; How stellar feedback simultaneously regulates star formation and drives outflows. Mon Not R Astron Soc 2017; 465 (2): 1682-1698. doi: 10.1093/mnras/stw2888
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64905
Deposited By: Ruth Sustaita
Deposited On:01 Mar 2016 21:33
Last Modified:10 Nov 2021 23:37

Repository Staff Only: item control page