We investigate the scenario in which primordial black holes (PBHs) with masses MPBH≲109 g undergo Hawking evaporation, around the big-bang nucleosynthesis (BBN) epoch. The evaporation process modifies the Universe's expansion rate and the baryon-to-photon ratio, leading to an alteration of the primordial abundance of light nuclei. We present numerical solutions for the set of equations describing this physics, considering different values of PBH masses and abundances at their formation, showing how their evaporation impacts the abundances of light nuclei, obtained by incorporating the nonstandard Hubble rate and baryon-to-photon ratio into the BBN code parthenope. The results are then used to place upper bounds for the PBH relative abundance at formation in the range 108 g≲MPBH≲109 g, providing the strongest constraints existing to date in this mass range.
Constraining the primordial black hole abundance through big-bang nucleosynthesis
Visinelli L.Writing – Original Draft Preparation
2025
Abstract
We investigate the scenario in which primordial black holes (PBHs) with masses MPBH≲109 g undergo Hawking evaporation, around the big-bang nucleosynthesis (BBN) epoch. The evaporation process modifies the Universe's expansion rate and the baryon-to-photon ratio, leading to an alteration of the primordial abundance of light nuclei. We present numerical solutions for the set of equations describing this physics, considering different values of PBH masses and abundances at their formation, showing how their evaporation impacts the abundances of light nuclei, obtained by incorporating the nonstandard Hubble rate and baryon-to-photon ratio into the BBN code parthenope. The results are then used to place upper bounds for the PBH relative abundance at formation in the range 108 g≲MPBH≲109 g, providing the strongest constraints existing to date in this mass range.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
