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Title: Ab Initio Simulations of a Supernova-driven Galactic Dynamo in an Isolated Disk Galaxy

Abstract

Here, we study the magnetic field evolution of an isolated spiral galaxy, using isolated Milky Way–mass galaxy formation simulations and a novel prescription for magnetohydrodynamic (MHD) supernova feedback. Our main result is that a galactic dynamo can be seeded and driven by supernova explosions, resulting in magnetic fields whose strength and morphology are consistent with observations. In our model, supernovae supply thermal energy and a low-level magnetic field along with their ejecta. The thermal expansion drives turbulence, which serves a dual role by efficiently mixing the magnetic field into the interstellar medium and amplifying it by means of a turbulent dynamo. The computational prescription for MHD supernova feedback has been implemented within the publicly available ENZO code and is fully described in this paper. This improves upon ENZO's existing modules for hydrodynamic feedback from stars and active galaxies. We find that the field attains microgauss levels over gigayear timescales throughout the disk. The field also develops a large-scale structure, which appears to be correlated with the disk's spiral arm density structure. We find that seeding of the galactic dynamo by supernova ejecta predicts a persistent correlation between gas metallicity and magnetic field strength. We also generate all-sky maps of themore » Faraday rotation measure from the simulation-predicted magnetic field, and we present a direct comparison with observations.« less

Authors:
ORCiD logo [1]; ORCiD logo [2];  [2];  [2];  [2]
  1. Univ. of Washington, Seattle, WA (United States); Stanford Univ., Stanford, CA (United States)
  2. Stanford Univ., Stanford, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1374392
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 843; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; magnetic fields; magnetohydrodynamics (MHD); methods: numerical; turbulence

Citation Formats

Butsky, Iryna, Zrake, Jonathan, Kim, Ji-hoon, Yang, Hung-I, and Abel, Tom. Ab Initio Simulations of a Supernova-driven Galactic Dynamo in an Isolated Disk Galaxy. United States: N. p., 2017. Web. doi:10.3847/1538-4357/aa799f.
Butsky, Iryna, Zrake, Jonathan, Kim, Ji-hoon, Yang, Hung-I, & Abel, Tom. Ab Initio Simulations of a Supernova-driven Galactic Dynamo in an Isolated Disk Galaxy. United States. doi:10.3847/1538-4357/aa799f.
Butsky, Iryna, Zrake, Jonathan, Kim, Ji-hoon, Yang, Hung-I, and Abel, Tom. Mon . "Ab Initio Simulations of a Supernova-driven Galactic Dynamo in an Isolated Disk Galaxy". United States. doi:10.3847/1538-4357/aa799f. https://www.osti.gov/servlets/purl/1374392.
@article{osti_1374392,
title = {Ab Initio Simulations of a Supernova-driven Galactic Dynamo in an Isolated Disk Galaxy},
author = {Butsky, Iryna and Zrake, Jonathan and Kim, Ji-hoon and Yang, Hung-I and Abel, Tom},
abstractNote = {Here, we study the magnetic field evolution of an isolated spiral galaxy, using isolated Milky Way–mass galaxy formation simulations and a novel prescription for magnetohydrodynamic (MHD) supernova feedback. Our main result is that a galactic dynamo can be seeded and driven by supernova explosions, resulting in magnetic fields whose strength and morphology are consistent with observations. In our model, supernovae supply thermal energy and a low-level magnetic field along with their ejecta. The thermal expansion drives turbulence, which serves a dual role by efficiently mixing the magnetic field into the interstellar medium and amplifying it by means of a turbulent dynamo. The computational prescription for MHD supernova feedback has been implemented within the publicly available ENZO code and is fully described in this paper. This improves upon ENZO's existing modules for hydrodynamic feedback from stars and active galaxies. We find that the field attains microgauss levels over gigayear timescales throughout the disk. The field also develops a large-scale structure, which appears to be correlated with the disk's spiral arm density structure. We find that seeding of the galactic dynamo by supernova ejecta predicts a persistent correlation between gas metallicity and magnetic field strength. We also generate all-sky maps of the Faraday rotation measure from the simulation-predicted magnetic field, and we present a direct comparison with observations.},
doi = {10.3847/1538-4357/aa799f},
journal = {The Astrophysical Journal (Online)},
number = 2,
volume = 843,
place = {United States},
year = {Mon Jul 10 00:00:00 EDT 2017},
month = {Mon Jul 10 00:00:00 EDT 2017}
}

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