2021 Fiscal Year Annual Research Report

The primordial magnetic field fluctuations, its evolution and the impact on Big-bang nucleosynthesis

Research Project

Project/Area Number	19J22167
Research Institution	National Astronomical Observatory of Japan
Principal Investigator	LUO Yudong 国立天文台, 科学研究部, 特別研究員(PD)
Project Period (FY)	2019-04-25 – 2022-03-31
Keywords	Primordial Black hole
Outline of Annual Research Achievements	In the most precise treatment of electromagnetic cascade spectrum, I included all feasible photodisintegration reactions and combine them with updated cross section data. I carried out accurate nucleosynthesis calculation and obtained a the reliable constraint on the PBH fraction among all dark matter component. Moreover, I investigated the mass function of PBHs in critical collapse model (i.e., PBHs formed via critical phenomena of gravitational collapse) and the impact on 3He abundance. In the past, the critical collapse mass function is thought of being practically indistinguishable from the monochromatic mass function. However, we show that the 3He abundance is sensitive to even small amounts of PBHs within the low-mass tail in the critical collapse mass function, which indicated that the nucleosynthesis can be a powerful tool to probe the extended mass function of PBHs. This work is publish on the Journal of Cosmology and Astrophysics.
Research Progress Status	令和3年度が最終年度であるため、記入しない。
Strategy for Future Research Activity	令和3年度が最終年度であるため、記入しない。