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arXiv · 2103.02815

Navigating the asteroid field: New evaporation constraints for primordial black holes as dark matter

Zachary S. C. Picker
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Abstract

Primordial black holes (PBHs) in the asteroid-mass range $(10^{-17}$--$10^{-12})~M_{\odot}$ almost entirely escape constraints as dark matter candidates. In the early universe, however, the Schwarzschild metric is no longer applicable and we must carefully consider PBH metrics with a proper cosmological embedding. In particular, the Thakurta solution stands out as perhaps the most adequate such solution. Notably, the Thakurta metric contains a time-dependent apparent horizon, proportional to the cosmological scale-factor. We show that this implies the PBHs are hotter than in the standard Schwarzschild case, and so evaporate significantly faster via Hawking radiation. By matter-radiation equality, PBHs up to masses of $\sim 10^{-12}~M_{\odot}$ have totally evaporated, and so cannot be a viable dark matter candidate.

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Zachary S. C. Picker. 2021-03-04. Navigating the asteroid field: New evaporation constraints for primordial black holes as dark matter. https://arxiv.org/abs/2103.02815

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