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

Journal Article · Mon Oct 10 00:00:00 EDT 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/830/1/17· OSTI ID:22667369

Boehle, A.; Ghez, A. M.; Meyer, L.; Yelda, S.; Albers, S.; Martinez, G. D.; Becklin, E. E.; Do, T.; Morris, M. R.; Sitarski, B.; Witzel, G. ^[1]; Schödel, R. ^[2]; Lu, J. R. ^[3]

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1. UCLA, Department of Physics and Astronomy, Los Angeles, CA 90095 (United States)
2. Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía S/N, E-18008 Granada (Spain)
3. Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)

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 {sub bh}) and distance ( R {sub o} ) of Sgr A*: M {sub bh} = (4.02 ± 0.16 ± 0.04) × 10{sup 6} M {sub ⊙} and 7.86 ± 0.14 ± 0.04 kpc. The uncertainties in M {sub bh} and R {sub 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{sup 6} M {sub ⊙} at 99.7% confidence, a factor of 3 lower compared to prior work.

• OSTI ID: 22667369
• Journal Information: Astrophysical Journal, Vol. 830, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BLACK HOLES
COMPARATIVE EVALUATIONS
DISTANCE
GALAXIES
GALAXY NUCLEI
IMAGES
MASS
OPTICS
ORBITS
PARTICLE TRACKS
QUASARS
REDUCTION
RESOLUTION
STARS
SUPERMASSIVE STARS