Prospects of future CMB anisotropy probes for primordial black holes

Abstract

Abstract Cascade of particles injected as Hawking Radiation from Primordial Black Holes (PBH) can potentially change the cosmic recombination history by ionizing and heating the intergalactic medium, which results in altering the anisotropy spectra of the Cosmic Microwave Background (CMB). In this paper, we study the expected sensitivity of several future CMB experiments in constraining the abundance of PBHs distributed in 1015∼1017 g mass window according to four mass functions: the monochromatic, log-normal, power-law and critical collapse models. Our result shows that future experiments, such as CMB-S4 and PICO, can improve the current Planck bounds by about two orders of magnitude. Most regions in PBH parameter space that are allowed by current CMB data, including monochromatically distributed PBHs with mass heavier than 3.8 × 1016 g, can be tested by upcoming missions with high significance.