Phenomenology of Magnetic Black Holes with Electroweak-Symmetric Coronas

TL;DR

This paper explores magnetic black holes with electroweak-symmetric coronas, their potential observational signatures, and sets new constraints on their abundance using astrophysical magnetic field data and neutrino detection.

Contribution

It introduces methods to search for primordial magnetic black holes and extends existing bounds on their abundance using large-scale magnetic fields and neutrino observations.

Findings

Magnetic black holes can have an abundance less than 0.6% of dark matter.

Large-scale magnetic fields in Andromeda extend Parker bound constraints.

Neutrino searches can surpass Parker bounds for certain black hole masses.

Abstract

Magnetically charged black holes (MBHs) are interesting solutions of the Standard Model and general relativity. They may possess a "hairy" electroweak-symmetric corona outside the event horizon, which speeds up their Hawking radiation and leads them to become nearly extremal on short timescales. Their masses could range from the Planck scale up to the Earth mass. We study various methods to search for primordially produced MBHs and estimate the upper limits on their abundance. We revisit the Parker bound on magnetic monopoles and show that it can be extended by several orders of magnitude using the large-scale coherent magnetic fields in Andromeda. This sets a mass-independent constraint that MBHs have an abundance less than $6 \times 10^{-3}$ times that of dark matter. MBHs can also be captured in astrophysical systems like the Sun, the Earth, or neutron stars. There, they can become non-extremal either from merging with an oppositely charged MBH or absorbing nucleons. The resulting Hawking radiation can be detected as neutrinos, photons, or heat. High-energy neutrino searches in particular can set a stronger bound than the Parker bound for some MBH masses, down to an abundance $10^{-7}$ of dark matter.