Gas Heating from Spinning and Non-Spinning Evaporating Primordial Black Holes

TL;DR

This paper investigates how evaporating primordial black holes, both spinning and non-spinning, heat surrounding gas, affecting dark matter constraints, with spinning PBHs providing tighter limits.

Contribution

It introduces a revised analysis of gas heating constraints from evaporating PBHs, highlighting the impact of black hole spin on these limits.

Findings

Constraints from Leo T dwarf galaxy are weaker than previously thought.

Spinning PBHs impose stronger limits on dark matter abundance than non-spinning PBHs.

Gas heating signatures depend significantly on black hole spin.

Abstract

Primordial black holes (PBHs) from the early Universe constitute a viable dark matter (DM) candidate and can span many orders of magnitude in mass. Light PBHs with masses around $10^{15}$ g contribute to DM and will efficiently evaporate through Hawking radiation at present time, leading to a slew of observable signatures. The emission will deposit energy and heat in the surrounding interstellar medium. We revisit the constraints from dwarf galaxy heating by evaporating non-spinning PBHs and find that conservative constraints from Leo T dwarf galaxy are significantly weaker than previously suggested. Furthermore, we analyse gas heating from spinning evaporating PBHs. The resulting limits on PBH DM abundance are found to be stronger for evaporating spinning PBHs than for non-spinning PBHs.