Secondary CMB temperature anisotropies from magnetic reheating

Abstract

Spatially fluctuating primordial magnetic fields (PMFs) inhomogeneously reheat the Universe when they dissipate deep inside the horizon before recombination. Such an energy injection turns into an additional photon temperature perturbation. We investigate secondary cosmic microwave background (CMB) temperature anisotropies originated from this mechanism, which we call {\it inhomogeneous magnetic reheating}. We find that it can bring us information about non-linear coupling between PMFs and primordial curvature perturbations parametrized by $b_{\mathrm{NL}}$, which should be important for probing the generation mechanism of PMFs. In fact, by using current CMB observations, we obtain an upper bound on the non-linear parameter as $\log (b_{\mathrm{NL}}(B_{\lambda }/\mathrm{nG}{)}^2)\lesssim -36.5n_B-94.0$ with $B_{\lambda }$ and $n_{\mathrm{B}}$ being a magnetic field amplitude smoothed over $\lambda =1\mathrm{Mpc}$ scale and a spectral index of the PMF power spectrum, respectively. Our constraints are far stronger than a previous forecast based on the future CMB spectral distortion anisotropy measurements because inhomogeneous magnetic reheating covers a much wider range of scales, i.e., $1{\mathrm{Mpc}}^{-1}\lesssim k\lesssim 10^{15}{\mathrm{Mpc}}^{-1}$.

10 pages, 3 figures

References in corpus (12)

• Gaia Data Release 2. Summary of the contents and survey properties
• The Cosmic Linear Anisotropy Solving System (CLASS) I: Overview
• CMB anisotropies from primordial inhomogeneous magnetic fields
• Silk damping at a redshift of a billion: a new limit on small-scale adiabatic perturbations
• On the non-Gaussian correlation of the primordial curvature perturbation with vector fields
• Probing correlations of early magnetic fields using mu-distortion
• CMB power spectra induced by primordial cross-bispectra between metric perturbations and vector fields
• Thermal Sunyaev-Zel'dovich effect in the intergalactic medium with primordial magnetic fields
• Cross-correlations between scalar perturbations and magnetic fields in bouncing universes
• Enhancing the cross-correlations between magnetic fields and scalar perturbations through parity violation
• Magnetic reheating
• Probing small-scale non-Gaussianity from anisotropies in acoustic reheating

Cited by in corpus (5)

• Limits on primordial magnetic fields from primordial black hole abundance
• Probing the primordial Universe with 21-cm line from cosmic dawn/epoch of reionization
• Imprints of primordial magnetic fields on intrinsic alignments of galaxies
• The parity-odd Intrinsic Bispectrum
• Revisiting constraints on primordial magnetic fields from spectral distortions of cosmic microwave background