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Evolution of galactic magnetic fields

Lookup NU author(s): Dr Luiz Felippe RodriguesORCiD, Dr Luke Chamandy, Professor Anvar ShukurovORCiD

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This is the authors' accepted manuscript of an article that has been published in its final definitive form by Oxford University Press, 2019.

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Abstract

We study the cosmic evolution of the magnetic fields of a large sample of spiral galaxies in a cosmologically representative volume by employing a semi-analytic galaxy formation model and numerical dynamo solver in tandem. We start by deriving time- and radius-dependent galaxy properties using the galform galaxy formation model, which are then fed into the nonlinear mean-field dynamo equations. These are solved to give the large-scale (mean) field as a function of time and galactocentric radius for a thin disc, assuming axial symmetry. A simple prescription for the evolution of the small-scale (random) magnetic field component is also adopted. We find that, while most massive galaxies are predicted to have large-scale magnetic fields at redshift z=0, a significant fraction of them are expected to contain negligible large-scale field. Our model indicates that, for most of the galaxies containing large-scale magnetic fields today, the mean-field dynamo becomes active at z<3. We compute the radial profiles of pitch angle, and find broad agreement with observational data for nearby galaxies.


Publication metadata

Author(s): Rodrigues LFS, Chamandy L, Shukurov A, Baugh CM, Taylor AR

Publication type: Article

Publication status: Published

Journal: Monthly Notices of the Royal Astronomical Society

Year: 2019

Volume: 483

Issue: 2

Pages: 2424-2440

Print publication date: 21/02/2019

Online publication date: 30/11/2018

Acceptance date: 28/11/2018

Date deposited: 28/01/2019

ISSN (print): 0035-8711

ISSN (electronic): 1365-2966

Publisher: Oxford University Press

URL: https://doi.org/10.1093/mnras/sty3270

DOI: 10.1093/mnras/sty3270


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