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AN IMPROVED DISTANCE AND MASS ESTIMATE FOR SGR A* FROM A MULTISTAR ORBIT ANALYSIS

A. BoehleUCLA, Department of Physics and Astronomy, Los Angeles, CA 90095, USA; [email protected]A. M. GhezUCLA, Department of Physics and Astronomy, Los Angeles, CA 90095, USA; [email protected]R. SchödelInstituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía S/N, E-18008 Granada, SpainL. MeyerUCLA, Department of Physics and Astronomy, Los Angeles, CA 90095, USA; [email protected]S. YeldaUCLA, Department of Physics and Astronomy, Los Angeles, CA 90095, USA; [email protected]S. AlbersUCLA, Department of Physics and Astronomy, Los Angeles, CA 90095, USA; [email protected]G. D. MartinezUCLA, Department of Physics and Astronomy, Los Angeles, CA 90095, USA; [email protected]E. E. BecklinUCLA, Department of Physics and Astronomy, Los Angeles, CA 90095, USA; [email protected]T. DoUCLA, Department of Physics and Astronomy, Los Angeles, CA 90095, USA; [email protected]Jessica R. LuInstitute for Astronomy, University of Hawaii, Honolulu, HI 96822, USAK. MatthewsDivision of Physics, Mathematics, and Astronomy, California Institute of Technology, MC 301-17, Pasadena, CA 91125, USAM. MorrisUCLA, Department of Physics and Astronomy, Los Angeles, CA 90095, USA; [email protected]B. SitarskiUCLA, Department of Physics and Astronomy, Los Angeles, CA 90095, USA; [email protected]Gunther WitzelUCLA, Department of Physics and Astronomy, Los Angeles, CA 90095, USA; [email protected]

2016en

ABI

Annotatsiya

ABSTRACT We present new, more precise measurements of the mass and distance of our Galaxy’s central supermassive black hole, Sgr A*. These results stem from a new analysis that more than doubles the time baseline for astrometry of faint stars orbiting Sgr A*, combining 2 decades of speckle imaging and adaptive optics data. Specifically, we improve our analysis of the speckle images by using information about a star’s orbit from the deep adaptive optics data (2005–2013) to inform the search for the star in the speckle years (1995–2005). When this new analysis technique is combined with the first complete re-reduction of Keck Galactic Center speckle images using speckle holography, we are able to track the short-period star S0-38 ( K -band magnitude = 17, orbital period = 19 yr) through the speckle years. We use the kinematic measurements from speckle holography and adaptive optics to estimate the orbits of S0-38 and S0-2 and thereby improve our constraints of the mass ( M bh ) and distance ( R o ) of Sgr A*: M bh = (4.02 ± 0.16 ± 0.04) × 10 6 M ⊙ and 7.86 ± 0.14 ± 0.04 kpc. The uncertainties in M bh and R o as determined by the combined orbital fit of S0-2 and S0-38 are improved by a factor of 2 and 2.5, respectively, compared to an orbital fit of S0-2 alone and a factor of ∼2.5 compared to previous results from stellar orbits. This analysis also limits the extended dark mass within 0.01 pc to less than 0.13 × 10 6 M ⊙ at 99.7% confidence, a factor of 3 lower compared to prior work.

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DOI: 10.3847/0004-637x/830/1/17

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