We assess the astrometric detectability of intermediate-mass black holes populating the inner parsec of the Milky Way Galaxy. The presence of these objects induces dynamical effects on Sgr A* and the star S2, which could be detected by next generation astrometric instruments that enable micro-arcsecond astrometry. An allowed population of ten 104M⊙ IMBHs within one parsec induces an angular shift of about 65 μas yr−1 on the position of Sgr A*, corresponding to a perpendicular velocity component magnitude of 1.6 km s−1. It also induces changes in the orbit of S2 that surpass those induced by general relativity but lie within observational constraints, generating a mean angular shift in periapse and apoapse of 62 μas and 970 μas respectively.
@article{arxiv.1807.02469,
title = {Astrometric Detection of Intermediate-Mass Black Holes At the Galactic Centre},
author = {Eden Girma and Abraham Loeb},
journal= {arXiv preprint arXiv:1807.02469},
year = {2018}
}