Gravitational search for near Earth black holes or other compact dark objects

TL;DR

This study uses a decade of superconducting gravimeter data to search for small tidal effects from near-Earth black holes or dark objects, setting upper mass limits and concluding such objects are highly unlikely.

Contribution

It provides the first observational constraints on the presence of small black holes or dark objects orbiting near Earth using gravimetric data.

Findings

No evidence of tidal accelerations from dark objects was found.

Excluded black holes or dark objects with masses >6.7x10^{13} kg within two Earth radii.

Constraints are particularly strong for objects with semi-major axes less than two Earth radii.

Abstract

Primordial black holes, with masses comparable to asteroids, are an attractive possibility for dark matter. In addition, other forms of dark matter could form compact dark objects (CDO). We search for small tidal accelerations from low mass black holes or CDOs orbiting near the Earth, and find none. Using about 10 years of data from the superconducting gravimeters in the Black Forest Observatory in South-Western Germany and at Djougou, Northern Benin in Western Africa we set an upper limit on the maximum mass of any dark object orbiting the Earth as a function of orbital radius. For semi-major axis less than two earth radii we exclude all black holes or CDOs with masses larger than 6.7x10^{13} kg. Lower mass primordial black holes may be strongly constrained by Hawking radiation. We conclude that near Earth black holes are extremely unlikely.