Reionization constraints on primordial magnetic fields

TL;DR

This study investigates how primordial magnetic fields influence the reionization history of the universe between redshifts 6 and 10, providing new constraints on their strength and impact.

Contribution

It offers the first comprehensive MCMC analysis linking primordial magnetic fields with reionization, constraining their strength and spectrum based on observational data.

Findings

Magnetic fields of 0.05-0.3 nG can significantly affect reionization.

Upper limits on magnetic field strength are set at 0.358, 0.120, 0.059 nG for different spectral indices.

Constraints are the strongest among current cosmological bounds.

Abstract

We study the impact of the extra density fluctuations induced by primordial magnetic fields on the reionization history in the redshift range: $6 < z < 10$. We perform a comprehensive MCMC physical analysis allowing the variation of parameters related to primordial magnetic fields (strength, $B_0$, and power-spectrum index $n_{\scriptscriptstyle \rm B}$), reionization, and $\Lambda$CDM cosmological model. We find that magnetic field strengths in the range: $B_0 \simeq 0.05{-}0.3$ nG (for nearly scale-free power spectra) can significantly alter the reionization history in the above redshift range and can relieve the tension between the WMAP and quasar absorption spectra data. Our analysis puts upper-limits on the magnetic field strength $B_0 < 0.358, 0.120, 0.059$ nG (95 % c.l.) for $n_{\scriptscriptstyle \rm B} = -2.95, -2.9, -2.85$, respectively. These represent the strongest magnetic field constraints among those available from other cosmological observables.