A Caltech Library Service

Feedback first: the surprisingly weak effects of magnetic fields, viscosity, conduction and metal diffusion on sub-L* galaxy formation

Su, Kung-Yi and Hopkins, Philip F. and Hayward, Christopher C. and Faucher-Giguère, Claude-André and Kereš, Dušan and Ma, Xiangcheng and Robles, Victor H. (2017) Feedback first: the surprisingly weak effects of magnetic fields, viscosity, conduction and metal diffusion on sub-L* galaxy formation. Monthly Notices of the Royal Astronomical Society, 471 (1). pp. 144-166. ISSN 0035-8711.

[img] PDF - Published Version
See Usage Policy.

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


Using high-resolution simulations with explicit treatment of stellar feedback physics based on the FIRE (Feedback In Realistic Environments) project, we study how galaxy formation and the interstellar medium (ISM) are affected by magnetic fields, anisotropic Spitzer–Braginskii conduction and viscosity, and sub-grid metal diffusion from unresolved turbulence. We consider controlled simulations of isolated (non-cosmological) galaxies but also a limited set of cosmological ‘zoom-in’ simulations. Although simulations have shown significant effects from these physics with weak or absent stellar feedback, the effects are much weaker than those of stellar feedback when the latter is modelled explicitly. The additional physics have no systematic effect on galactic star formation rates (SFRs). In contrast, removing stellar feedback leads to SFRs being overpredicted by factors of ∼10–100. Without feedback, neither galactic winds nor volume-filling hot-phase gas exist, and discs tend to runaway collapse to ultra-thin scaleheights with unphysically dense clumps congregating at the galactic centre. With stellar feedback, a multi-phase, turbulent medium with galactic fountains and winds is established. At currently achievable resolutions and for the investigated halo mass range 10^(10)–10^(13) M⊙, the additional physics investigated here (magnetohydrodynamic, conduction, viscosity, metal diffusion) have only weak (∼10 per cent-level) effects on regulating SFR and altering the balance of phases, outflows or the energy in ISM turbulence, consistent with simple equipartition arguments. We conclude that galactic star formation and the ISM are primarily governed by a combination of turbulence, gravitational instabilities and feedback. We add the caveat that active galactic nucleus feedback is not included in the present work.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Su, Kung-Yi0000-0003-1598-0083
Hopkins, Philip F.0000-0003-3729-1684
Hayward, Christopher C.0000-0003-4073-3236
Faucher-Giguère, Claude-André0000-0002-4900-6628
Kereš, Dušan0000-0002-1666-7067
Ma, Xiangcheng0000-0001-8091-2349
Robles, Victor H.0000-0002-9497-9963
Alternate Title:Feedback first: the surprisingly weak effects of magnetic fields, viscosity, conduction, and metal diffusion on galaxy formation
Additional Information:© 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 June 9. Received 2017 April 22; in original form 2016 July 17. Published: 13 June 2017. We thank Ai-Lei Sun, Shu-heng Shao, Eliot Quataert and Cameron Hummels for useful discussions. 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. CCH is grateful to the Gordon and Betty Moore Foundation for financial support. The Flatiron Institute is supported by the Simons Foundation. CAFG was supported by NSF through grants AST-1412836 and AST-1517491, by NASA through grant NNX15AB22G, and by STScI through grants HST-AR- 14293.001-A and HST-GO-14268.022-A. DK was supported in part by NSF grant AST-1412153. Numerical calculations were run on the Caltech compute cluster ‘Zwicky’ (NSF MRI award #PHY-0960291) and allocation TG-AST130039 granted by the Extreme Science and Engineering Discovery Environment (XSEDE) supported by the NSF.
Group:TAPIR, Astronomy Department
Funding AgencyGrant Number
Alfred P. Sloan FoundationUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Simons FoundationUNSPECIFIED
Subject Keywords:conduction, MHD, turbulence, methods: numerical, ISM: jets and outflows, ISM: structure
Issue or Number:1
Record Number:CaltechAUTHORS:20161212-093805711
Persistent URL:
Official Citation:Kung-Yi Su, Philip F. Hopkins, Christopher C. Hayward, Claude-André Faucher-Giguère, Dušan Kereš, Xiangcheng Ma, Victor H. Robles; Feedback first: the surprisingly weak effects of magnetic fields, viscosity, conduction and metal diffusion on sub-L* galaxy formation, Monthly Notices of the Royal Astronomical Society, Volume 471, Issue 1, 11 October 2017, Pages 144–166,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:72709
Deposited By: Tony Diaz
Deposited On:12 Dec 2016 18:26
Last Modified:07 Apr 2020 18:44

Repository Staff Only: item control page