Constraint on primordial magnetic fields in the light of ARCADE 2 and EDGES observations

Abstract

We study the constraints on primordial magnetic fields (PMFs) in the light of the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) low-band observation and Absolute Radiometer for Cosmology, Astrophysics and Diffuse Emission (ARCADE 2). ARCADE 2 observation detected extra-galactic excess radio radiation in the frequency range 3–90 GHz. The enhancement in the radio radiation is also supported by the first station of the Long Wavelength Array (LWA1) in the frequency range 40–80 MHz. The presence of early radiation excess over the cosmic microwave background can not be completely ruled out, and it may explain the EDGES anomaly. In the presence of decaying PMFs, 21 cm differential brightness temperature can modify due to the heating of the gas by decaying magnetic fields, and we can constraint the magnetic fields. For excess radiation fraction ($$A_r$$ A r ) to be LWA1 limit, we show that the upper bound on the present-day magnetic field strength, $$B_0$$ B 0 , on the scale of 1 Mpc is $$\lesssim 3.7$$ ≲ 3.7 nG for spectral index $$n_B=-2.99$$ n B = - 2.99 . While for $$n_B=-1$$ n B = - 1 , we get $$B_0\lesssim 1.1\times 10^{-3}$$ B 0 ≲ 1.1 × 10 - 3 nG. We also discuss the effects of first stars on IGM gas evolution and the allowed value of $$B_0$$ B 0 . For $$A_r$$ A r to be LWA1 limit, we get the upper constraint on magnetic field to be $$B_0(n_B=-2.99)\lesssim 4.9\times 10^{-1}$$ B 0 ( n B = - 2.99 ) ≲ 4.9 × 10 - 1 nG and $$B_0(n_B=-1)\lesssim 3.7\times 10^{-5}$$ B 0 ( n B = - 1 ) ≲ 3.7 × 10 - 5 nG. By decreasing excess radiation fraction below the LWA1 limit, we get a more stringent bound on $$B_0$$ B 0 .

Constraining spinning primordial black holes with global 21-cm signal

“…After the formation of the first stars (z ∼ 30), their Lyα radiation cause the hyperfine transition in the neutral hydrogen atom, and gas coupling to the spin temperature (by Wouthuysen-Field effect) starts dominate over other effects [60,[107][108][109][110][111]. Therefore, the spin temperature, T S T gas at redshift 17.2 [49]. Heating of the gas due to X-ray radiation produced by first stars starts dominating after z ∼ 17 [49,67,[112][113][114].…”

“…To resolve this discrepancy, either one has to increase the background radio radiation or decrease the gas temperature. Both the scenarios have been explored in several literatures [44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61]. However, increasing the background radio radiation or cooling the IGM gas by the non-standard mechanisms are not well known and are a debatable issue [62][63][64][65][66][67][68][69][70][71].…”

Distribution function of nuclei from $e^\pm$ scattering in the presence of a strong primordial magnetic field

“…Ultimately, what we can observe with current measurements are signatures of large-scale PMFs which could have been generated in the inflationary epoch before the big bang [32]. Constraints on the PMF [26] have been deduced from various astronomical observations such as the CMB temperature and polarization from gravitational [33][34][35][36][37][38][39] and heating effects [40], redshifted 21 cm signal from heating effects [31,[41][42][43], ultra-faint dwarf galaxies from gravitational effects [44], and gravitational waves (at very small scales) [45].…”

Magnetogenesis and the Cosmic Web: A Joint Challenge for Radio Observations and Numerical Simulations

“…Other stringent limits have been suggested by modelling magnetic effects on post-recombination heating e.g., [57][58][59] or by the small-scale baryonic density fluctuation induced by primordial magnetic fields, which would alter CMB anisotropies by promoting to inhomogeneous recombination and heating e.g., [60][61][62]. Recent limits for the average present-day magnetisation of the Universe have also been derived by the level of excess in diffuse radio emission detected by ARCADE2 and EDGES 21cm line experiments, yielding ≤10 −3 -0.3 nG depending on the unknown spectral index of primordial seed fields [63].…”