Effect of primordial magnetic fields on the ionization history

Journal
Date Issued
2015
Author(s)
Chluba, Jens
•
•
•
Rubiño-Martín, J. A.
DOI
Description
We wish to thank Yacine Ali-Haïmoud, E. Komatsu, K. Kunze, G. Sigl and K. Subramanian for comments and suggestions. JC is supported by the Royal Society as a Royal Society University Research Fellow at the University of Cambridge, UK JARM acknowledges financial support from the Spanish Ministry of Economy and Competitiveness under the 2011 Severo Ochoa Program MINECO SEV-2011-0187, and the Consolider-Ingenio project CSD2010-00064 (EPI: Exploring the Physics of Inflation).
Abstract
Primordial magnetic fields (PMF) damp at scales smaller than the photon diffusion and free-streaming scale. This leads to heating of ordinary matter (electrons and baryons), which affects both the thermal and ionization history of our Universe. Here, we study the effect of heating due to ambipolar diffusion and decaying magnetic turbulence. We find that changes to the ionization history computed with recfast are significantly overestimated when compared with CosmoRec. The main physical reason for the difference is that the photoionization coefficient has to be evaluated using the radiation temperature rather than the matter temperature. A good agreement with CosmoRec is found after changing this aspect. Using Planck 2013 data and considering only the effect of PMF-induced heating, we find an upper limit on the rms magnetic field amplitude of B0 ≲ 1.1 nG (95 per cent c.l.) for a stochastic background of PMF with a nearly scale-invariant power spectrum. We also discuss uncertainties related to the approximations for the heating rates and differences with respect to previous studies. Our results are important for the derivation of constraints on the PMF power spectrum obtained from measurements of the cosmic microwave background anisotropies with full-mission Planck data. They may also change some of the calculations of PMF-induced effects on the primordial chemistry and 21cm signals.
Volume
451
Issue
2
Start page
2244
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2015MNRAS.451.2244C
Rights
open.access
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