The search for a primordial magnetic field

Abstract

Magnetic fields appear wherever plasma and currents can be found. As such, they thread through all scales in Nature. It is natural, therefore, to suppose that magnetic fields might have been formed within the high temperature environments of the big bang. Such a primordial magnetic field (PMF) would be expected to arise from and/or influence a variety of cosmological phenomena such as inflation, cosmic phase transitions, big bang nucleosynthesis, the cosmic microwave background (CMB) temperature and polarization anisotropies, the cosmic gravity wave background, and the formation of largescale structure. In this review, we summarize the development of theoretical models for analyzing the observational consequences of a PMF. We also summarize the current state of the art in the search for observational evidence of a PMF. In particular we review the framework needed to calculate the effects of a PMF power spectrum on the CMB and the development of large scale structure. We summarize the current constraints on the PMF amplitude B λ and the power spectral index n B and discuss prospects for better determining these quantities in the near future.

Reionization constraints on primordial magnetic fields

“…Yamazaki et al 2012, Yamazaki 2014. These fields can generate density perturbations in addition to the ΛCDM model in the post-recombination epoch (Wasserman 1978, Kim, Olinto, & Rosner 1996, Gopal & Sethi 2003).…”

The New BBN Model with the Photon Cooling, X Particle, and the Primordial Magnetic Field

“…We find that the PMF energy density ( ) and the parameters of the X particle ( and ) have no significant degeneracies. The PMF parameters, however, can be strongly constrained by the CMB and the matter power spectrum (MPS) observations [6][7][8][9][10][11][12][13]. Therefore, if we limit the PMF energy density by the future CMB and MPS observations more strongly, we can limit the combined effects of the photon cooling, the X decay, and the PMF on BBN mote strongly and derive tighter constraints on these parameters.…”

“…It is called ``Li problem'' [2]. To resolve this Li problem, previous studies have proposed three ideas: the photon cooling (possibly via the Bose-Einstein condensation of a scalar particle) [3,4], the decay of a long-lived X particle (possibly the next-to-lightest supersymmetric particle) [5], and an energy density of a primordial magnetic field (PMF) [6][7][8][9][10][11][12][13]. We introduce combined effects of these on BBN, and derive constraint on the X particles and the PMF parameters by observed light element abundances with likelihood analysis.…”

Big Bang nucleosynthesis and the origin and evolution of space-time

“…Regarding item 11, the formation existence of extra dimensions can lead to time varying physical constants [31]. Regarding items 3, 6,7, 12 some scenarios for inflation, reheating and baryogenesis and associated magnetic field generation can lead to a modified expansion rate [33,37]. Similarly the early formation of dark matter and dark energy [34,32] can alter the expansion rate.…”

“…Such a PMF, however, could have influenced a variety of phenomena in the early universe such as the cosmic microwave background (CMB), (e.g. [37] and refs. therein).…”