Searching for Signal of Primordial Black Hole from CMB Lensing and $\gamma$-ray Emissions

TL;DR

This paper investigates primordial black holes by correlating gamma-ray emissions and CMB lensing, aiming to constrain their abundance in specific mass ranges using future observational sensitivities.

Contribution

It introduces a novel method of constraining PBH fractions through correlation of gamma-ray emissions and CMB lensing, including models with spins, and assesses future observational prospects.

Findings

Potential to tightly constrain PBH fractions in the mass range 10^{16} - 5×10^{17} g.

Inclusion of PBH spin models improves constraints by an order of magnitude.

Future experiments like CMB-S4 and e-ASTROGAM can significantly enhance detection sensitivity.

Abstract

In this $\textit{Letter}$, we search for the signal of the primordial black holes (PBHs) by correlating the $\gamma$-ray emissions in the MeV energy band produced by the Hawking evaporation and the lensing effect of the cosmic microwave background (CMB). We use the conservative case of the astrophysical model as much as possible in the calculations, since the potential astrophysical origins dominate the observed emission in the MeV energy band. By carefully discussing the appropriate energy bands corresponding to different PBHs masses, it is worth expecting a tight constraint on the fraction of the Schwarzschild PBHs in the mass range of $10^{16} - 5\times10^{17}\,{\rm g}$, by simulations of the sensitivity of the future CMB-S4 project and the $\gamma$-ray telescope e-ASTROGAM. Furthermore, we also consider the PBHs model with spins, and find that the constraining ability of the PBHs fraction from the correlation between CMB lensing and $\gamma$-ray emissions can be improved by another order of magnitude, which could importantly fill the gaps with PBHs fraction limits in the mass range of $5\times 10^{17} - 2\times 10^{18}\,{\rm g}$.