2025/01/24 by D. Montanino, Manno, Marco, Montanino, Daniele
Engineering · Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #High Energy Physics - Phenomenology (hep-ph) #Particle Accelerators and Free-Electron Lasers
paper · pdf · doi:10.48550/arxiv.2501.14589
openalex publication_date 2025/01/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Light Primordial Black Holes (LPBHs) with masses in the range 10 g ≤ M\rm BH ≤ 109 g, although they evaporate before Big Bang Nucleosynthesis, can play a significant role in the production of both Dark Matter and Dark Radiation. In particular, LPBHs can evaporate into light axions or axion-like particles (ALPs) with masses ma \lesssim MeV, contributing to the effective number of neutrino species, ΔN\rm eff. Additionally, heavy scalar particles known as moduli, predicted by String Theory, can be produced both via Hawking evaporation and through amplification by a mechanism called Superradiance Instability in the case of spinning PBHs. These moduli can subsequently decay into ALPs, further amplifying their abundance. In this work, we calculate the number density of ALPs in the presence of moduli enhanced by Superradiance for Kerr PBHs. Using current limits on ΔN\rm eff from Planck satellite observations, we derive updated constraints on this scenario.