Astrometric Detection of Intermediate-Mass Black Holes At the Galactic Centre

TL;DR

This paper evaluates the potential for next-generation astrometric instruments to detect intermediate-mass black holes near the Galactic Center by analyzing their dynamical effects on Sgr A* and star S2.

Contribution

It provides a detailed assessment of the astrometric signatures caused by a population of IMBHs, highlighting their detectability with micro-arcsecond precision instruments.

Findings

IMBHs induce measurable shifts in Sgr A*'s position.

IMBHs cause orbital changes in star S2 exceeding general relativity effects.

Detectable angular shifts are within observational constraints.

Abstract

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 $10^4~M_{\odot}$ IMBHs within one parsec induces an angular shift of about 65 $\mu$as 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 $\mu$as and 970 $\mu$as respectively.