Constraining the primordial magnetic fields with the 21-cm global signal
by
Teppei Minoda
→
Europe/Paris
salle des séminaires (IAP)
salle des séminaires
IAP
Description
While the existence of the magnetic fields in galaxies and galaxy clusters is reported, their origin is still unknown. An attractive scenario is that the Primordial Magnetic Fields (PMFs), which are the tiny seed fields generated in the early universe, evolve to become the astrophysical magnetic fields. However, the PMFs are not yet confirmed observationally, and it is an open question whether or not the PMFs exist, and what their strength is. To solve this problem, many efforts have been made to investigate the observational signatures of the PMFs. Currently, the upper limits on the PMFs are given by the Cosmic Microwave Background (CMB) and the Large-Scale Structure (LSS) observations.
In this talk, I will introduce my contribution to the constraints on the PMFs with the HI 21-cm line global signal measurement. In the cosmological context, the observation of the redshifted 21-cm line can probe the cosmic history of the baryon gas temperature in the Cosmic Dawn (CD) and the Epoch of Reionization (EoR). The PMFs can strongly affect the baryon gas thermal history during these periods through their energy dissipation. We calculate the baryon gas temperature history including the heating due to the PMF dissipation until the EoR. The recent 21-cm line signal measurement by Experiment to Detect the Global EoR Signature (EDGES) gives a clue to the thermal history of baryon gas around the CD and EoR. Employing the measurement of EDGES, we can set the stringent upper limit on the PMFs, which is less than sub-nano Gauss.
