Increasing the Scientific Return of Stellar Orbits at the Galactic Center

TL;DR

This paper enhances the precision of stellar orbit measurements near the Galactic Center's supermassive black hole by improving astrometric accuracy through better distortion modeling and atmospheric correction, enabling more detailed orbital analysis.

Contribution

It introduces a systematic distortion model based on M92 to significantly improve astrometric measurements near the SMBH.

Findings

Astrometric precision improved by a factor of three.

Increased likelihood that the SMBH is at rest relative to the nuclear star cluster.

Extended the radius for reliable stellar orbital parameter estimates.

Abstract

We report a factor of $\sim$3 improvement in Keck Laser Guide Star Adaptive Optics (LGSAO) astrometric measurements of stars near the Galaxy's supermassive black hole (SMBH). By carrying out a systematic study of M92, we have produced a more accurate model for the camera's optical distortion. Updating our measurements with this model, and accounting for differential atmospheric refraction, we obtain estimates of the SMBH properties that are a factor of $\sim$2 more precise, and most notably, increase the likelihood that the black hole is at rest with respect to the nuclear star cluster. These improvements have also allowed us to extend the radius to which stellar orbital parameter estimates are possible by a factor of 2.