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 1015 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 analyze 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.
Highlights
While significant attention has been devoted to larger mass Primordial black holes (PBHs), it has been realized recently that light PBHs can result in a larger variety of observable signatures than previously thought and is ripe for further exploration
Particle emission from currently evaporating PBHs produces a variety of signatures, providing insight into this region of PBH dark matter (DM) parameter space
Throughout this work, we focus on the well-modeled Leo T dwarf galaxy as our target system due to its desirable cooling, gas, and DM properties
Summary
Primordial black holes (PBHs), formed in the early Universe prior to any galaxies and stars, are a viable candidate for DM (e.g., [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31]). Observations from dwarf galaxies (in particular, Leo T) have been used to constrain stellar and intermediate-mass PBHs by considering heating of interstellar medium (ISM) gas due to PBH interactions [69]. This represents a new signature not previously considered for PBHs. Subsequently, Ref. [70] considered heating of ISM gas due to light evaporating non-rotating PBHs. In this work, we revisit and provide an alternative treatment of gas heating due to evaporating PBHs, focusing on the dwarf galaxy Leo T.
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