Abstract Details

Name: Shikhar Mittal
Affiliation: Tata Institute of Fundamental Research, Mumbai
Conference ID: ASI2021_67
Title : Lyman-α coupling and heating at Cosmic Dawn
Authors and Co-Authors : Shikhar Mittal (TIFR), Girish Kulkarni (TIFR)
Abstract Type : Oral
Abstract Category : General Relativity and Cosmology
Abstract : The global 21-cm signal from the cosmic dawn is affected by a variety of heating and cooling processes. We investigate the impact of heating due to Lyman-α (Ly α) photons on the global 21-cm signal during cosmic dawn using an analytical expression of the spectrum around the Ly α resonance based on the so-called ‘wing approximation’. We perform a short parameter study by varying the Ly α background intensity by four orders of magnitude and establish that a strong Ly α background is necessary, although not sufficient, in order to reproduce the recently detected stronger-than-expected 21-cm signal by the EDGES Collaboration. We show that the magnitude of this Ly α heating is smaller than previously estimated in the literature by two orders of magnitude or more. As a result, even a strong Ly α background is consistent with the EDGES measurement of the global 21-cm absorption signal.