Journal Article

Random primordial magnetic fields and the gas content of dark matter haloes

Rafael S. de Souza, Luiz Felippe S. Rodrigues and Reuven Opher

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 410, issue 4, pages 2149-2155
Published in print February 2011 | ISSN: 0035-8711
Published online January 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.17588.x
Random primordial magnetic fields and the gas content of dark matter haloes

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We recently predicted the existence of random primordial magnetic fields (RPMFs) in the form of randomly oriented cells with dipole-like structure with a cell size L0 and an average magnetic field B0. Here, we investigate models for primordial magnetic field with a similar web-like structure, and other geometries, differing perhaps in L0 and B0. The effect of RPMF on the formation of the first galaxies is investigated. The filtering mass, MF, is the halo mass below which baryon accretion is severely depressed. We show that these RPMF could influence the formation of galaxies by altering the filtering mass and the baryon gas fraction of a halo, fg. The effect is particularly strong in small galaxies. We find, for example, for a comoving B0= 0.1 μG, and a reionization epoch that starts at zs= 11 and ends at ze= 8, for L0= 100 pc at z= 12, the fg becomes severely depressed for M < 107 M, whereas for B0= 0 the fg becomes severely depressed only for much smaller masses, M < 105 M. We suggest that the observation of MF and fg at high redshifts can give information on the intensity and structure of primordial magnetic fields.

Keywords: magnetic fields; galaxies: formation; galaxies: haloes; large-scale structure of Universe

Journal Article.  4452 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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