Colloquium on Nov. 7, 2024

Probing the primordial magnetic fields

Speaker: Teppei Minoda (Tsinghua University)

Venue: SWIFAR Building 2111

Time: 16:00 PM, Thursday, Nov. 7, 2024

Abstract:

The origin of cosmic magnetic fields is an open question in cosmology and astrophysics. One possible scenario is that the Primordial Magnetic Fields (PMFs), which are generated in the early universe, are amplified to become the currently observed magnetic fields. To confirm this scenario, many efforts have been made to investigate the observational signatures of the PMFs. Several upper limits on the PMFs have been obtained by the Cosmic Microwave Background (CMB) and the Large-Scale Structure (LSS) observations. In this talk, I will introduce the brief review of the constraints on the PMFs and my contribution using 21cm line global signal experiment. The redshifted 21cm line can be used to explore thermal history of the diffuse baryon gas at Cosmic Dawn of the universe. We study the effects of PMFs on the baryon gas temperature, when MHD processes dissipate the magnetic energy. We show that nano-Gauss PMFs can heat the baryon gas in IGM up to ~ 1000 K, and that the constraints on the PMF amplitude and scale-dependence are given by the 21cm global signal observations.