1. Magnetic fields from compensated isocurvature perturbations
- Author
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Jordan Flitter, Cyril Creque-Sarbinowski, Marc Kamionkowski, and Liang Dai
- Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,FOS: Physical sciences ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
Compensated isocurvature perturbations (CIPs) are perturbations to the primordial baryon density that are accompanied by dark-matter-density perturbations so that the total matter density is unperturbed. Such CIPs, which may arise in some multi-field inflationary models, can be long-lived and only weakly constrained by current cosmological measurements. Here we show that the CIP-induced modulation of the electron number density interacts with the electron-temperature fluctuation associated with primordial adiabatic perturbations to produce, via the Biermann-battery mechanism, a magnetic field in the post-recombinaton Universe. Assuming the CIP amplitude saturates the current BBN bounds, this magnetic field can be stronger than $10^{-15}\,\mathrm{nG}$ at $z\simeq20$ and stronger by an order of magnitude than that (produced at second order in the adiabatic-perturbation amplitude) in the standard cosmological model, and thus can serve as a possible seed for galactic dynamos., 7 pages, 2 figures, version accepted for publication in PRD
- Published
- 2023