Formation of hot spots around small primordial black holes

Minxi He, Kazunori Kohri, Kyohei Mukaida, Masaki Yamada

Research output: Contribution to journalArticlepeer-review


In this paper, we investigate the thermalization of Hawking radiation from primordial black holes (PBHs) in the early Universe, taking into account the interference effect on thermalization of high energy particles, known as Landau-Pomeranchuk-Migdal (LPM) effect. Small PBHs with masses ≲ 109 g completely evaporate before the big bang nucleosynthesis (BBN). The Hawking radiation emitted from these PBHs heats up the ambient plasma with temperature lower than the Hawking temperature, which results in a non-trivial temperature profile around the PBHs, namely a hot spot surrounding a PBH with a broken power-law tail. We find that the hot spot has a core with a radius much larger than the black hole horizon and its highest temperature is independent of the initial mass of the PBH such as 2 × 109 GeV × (α/0.1)19/3, where α generically represents the fine-structure constants. We also briefly discuss the implications of the existence of the hot spot for phenomenology.

Original languageEnglish
Article number027
JournalJournal of Cosmology and Astroparticle Physics
Issue number1
Publication statusPublished - 2023 Jan 1


  • particle physics - cosmology connection
  • physics of the early universe
  • primordial black holes

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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