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Stellar feedback strongly alters the amplification and morphology of galactic magnetic fields

Su, Kung-Yi and Hayward, Christopher C. and Hopkins, Philip F. and Quataert, Eliot and Faucher-Giguère, Claude-André and Kereš, Dušan (2018) Stellar feedback strongly alters the amplification and morphology of galactic magnetic fields. Monthly Notices of the Royal Astronomical Society: Letters, 473 (1). L111-L115. ISSN 1745-3925. doi:10.1093/mnrasl/slx172.

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Using high-resolution magnetohydrodynamic simulations of idealized, non-cosmological galaxies, we investigate how cooling, star formation and stellar feedback affect galactic magnetic fields. We find that the amplification histories, saturation values and morphologies of the magnetic fields vary considerably depending on the baryonic physics employed, primarily because of differences in the gas density distribution. In particular, adiabatic runs and runs with a subgrid (effective equation of state) stellar feedback model yield lower saturation values and morphologies that exhibit greater large-scale order compared with runs that adopt explicit stellar feedback and runs with cooling and star formation but no feedback. The discrepancies mostly lie in gas denser than the galactic average, which requires cooling and explicit fragmentation to capture. Independent of the baryonic physics included, the magnetic field strength scales with gas density as B ∝ n^(2/3), suggesting isotropic flux freezing or equipartition between the magnetic and gravitational energies during the field amplification. We conclude that accurate treatments of cooling, star formation and stellar feedback are crucial for obtaining the correct magnetic field strength and morphology in dense gas, which, in turn, is essential for properly modelling other physical processes that depend on the magnetic field, such as cosmic ray feedback.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Su, Kung-Yi0000-0003-1598-0083
Hayward, Christopher C.0000-0003-4073-3236
Hopkins, Philip F.0000-0003-3729-1684
Quataert, Eliot0000-0001-9185-5044
Faucher-Giguère, Claude-André0000-0002-4900-6628
Kereš, Dušan0000-0002-1666-7067
Additional Information:© 2017 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 October 13. Received 2017 October 9; in original form 2017 July 14. Published: 17 October 2017. 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, NSF Collaborative Research Grant #1411920 and CAREER grant #1455342. CAFG was supported by NSF through grants AST-1412836 and AST-1517491, and by NASA through grant NNX15AB22G. DK was supported by NSF grant AST-1412153 and a Cottrell Scholar Award from the Research Corporation for Science Advancement. 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
Simons FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Research CorporationUNSPECIFIED
Subject Keywords:MHD– methods: numerical – ISM: jets and outflows – ISM: structure – galaxy: evolution
Issue or Number:1
Record Number:CaltechAUTHORS:20171031-193058430
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Official Citation:Kung-Yi Su, Christopher C Hayward, Philip F Hopkins, Eliot Quataert, Claude-André Faucher-Giguère, Dušan Kereš; Stellar feedback strongly alters the amplification and morphology of galactic magnetic fields, Monthly Notices of the Royal Astronomical Society: Letters, Volume 473, Issue 1, 1 January 2018, Pages L111–L115,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:82827
Deposited By: Joy Painter
Deposited On:01 Nov 2017 12:54
Last Modified:15 Nov 2021 19:53

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