The Proper Motion of Sagittarius A*. II. The Mass of Sagittarius A*

Reid, M. J.; Brunthaler, A.

doi:10.1086/424960

Cited by 759 publications

(807 citation statements)

References 39 publications

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“…Reid & Brunthaler (2004) measured the apparent proper motion of Sgr A * , which is due only to the galactic orbit of the Sun if the SMBH is assumed to be at the center of the Galaxy. This measurement gave a ratio of the circular rotation speed at the radius of the Sun (Θ o ) and R o of 29.45±0.15 km s −1 kpc −1 .…”

Section: Scientific Implications Of New Constraints On M Bh and R Omentioning

confidence: 99%

An Improved Distance and Mass Estimate for SGR A* From a Multistar Orbit Analysis

Boehle

Ghez

Schödel

et al. 2016

ApJ

348

413

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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)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013) to inform the search for the star in the speckle years (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(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 e 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 e at 99.7% confidence, a factor of 3 lower compared to prior work.

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Section: Scientific Implications Of New Constraints On M Bh and R Omentioning

confidence: 99%

An Improved Distance and Mass Estimate for SGR A* From a Multistar Orbit Analysis

Boehle

Ghez

Schödel

et al. 2016

ApJ

348

413

View full text Add to dashboard Cite

show abstract

“…As mentioned earlier, R0 has been set to 8.34 kpc (Reid et al 2014). The value of Ω⊙ is well constrained by the proper motions of Sgr A * measured by Reid & Brunthaler (2004). For VR,⊙, we take the value of −7.01 km s −1 determined by Huang et al (2015b).…”

Section: Kinematical Modelmentioning

confidence: 99%

The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution

Huang

Liu

Yuan

et al. 2016

Mon. Not. R. Astron. Soc.

161

179

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The rotation curve (RC) of the Milky Way out to ∼ 100 kpc has been constructed using ∼ 16, 000 primary red clump giants (PRCGs) in the outer disk selected from the LSS-GAC and the SDSS-III/APOGEE survey, combined with ∼ 5700 halo K giants (HKGs) selected from the SDSS/SEGUE survey. To derive the RC, the PRCG sample of the warm disc population and the HKG sample of halo stellar population are respectively analyzed using a kinematical model allowing for the asymmetric drift corrections and re-analyzed using the spherical Jeans equation along with measurements of the anisotropic parameter β currently available. The typical uncertainties of RC derived from the PRCG and HKG samples are respectively 5-7 km s −1 and several tens km s −1 . We determine a circular velocity at the solar position, V c (R 0 ) = 240 ± 6 km s −1 and an azimuthal peculiar speed of the Sun, V ⊙ = 12.1 ± 7.6 km s −1 , both in good agreement with the previous determinations. The newly constructed RC has a generally flat value of 240 km s −1 within a Galactocentric distance r of 25 kpc and then decreases steadily to 150 km s −1 at r ∼ 100 kpc. On top of this overall trend, the RC exhibits two prominent localized dips, one at r ∼ 11 kpc and another at r ∼ 19 kpc. From the newly constructed RC, combined with other constraints, we have built a parametrized mass model for the Galaxy, yielding a virial mass of the Milky Way's dark matter halo of 0.90 +0.07 −0.08 × 10 12 M ⊙ and a local dark matter density, ρ ⊙,dm = 0.32 +0.02 −0.02 GeV cm −3 .

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“…A 4×10 6  M black hole is coincident with the compact nonthermal radio source SgrA * at the center of the Galaxy (Reid & Brunthaler 2004;Ghez et al 2008;Gillessen et al 2009). The estimated mass accretion rate onto Sgr A * is several orders of magnitude smaller than the rate at which young, windy stars in the innermost 0.5 pc supply mass to the Bondi radius of Sgr A * (Coker & Melia 1997;Cuadra et al 2006Cuadra et al , 2008.…”

Section: Introductionmentioning

confidence: 99%

SGR A* and Its Environment: Low-Mass Star Formation, the Origin of X-Ray Gas and Collimated Outflow

Yusef‐Zadeh

Wardle

Schödel

et al. 2016

ApJ

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We present high-resolution multiwavelength radio continuum images of the region within 150″ of SgrA * , revealing a number of new extended features and stellar sources in this region. First, we detect a continuous 2″ east-west ridge of radio emission, linking SgrA * and a cluster of stars associated with IRS 13 N and IRS 13E. The ridge suggests that an outflow of east-west blob-like structures is emerging from SgrA * . In particular, we find arc-like radio structures within the ridge with morphologies suggestive of photoevaporative protoplanetary disks. We use infrared K s and L′ fluxes to show that the emission has similar characteristics to those of a protoplanetary disk irradiated by the intense radiation field at the Galactic center. This suggests that star formation has taken place within the S-cluster 2″ from SgrA * . We suggest that the diffuse X-ray emission associated with Sgr A * is due to an expanding hot wind produced by the mass loss from B-type main sequence stars, and/or the disks of photoevaporation of low mass young stellar objects (YSOs) at a rate of ∼10 −6  M yr −1 . The proposed model naturally reduces the inferred accretion rate and is an alternative to the inflow-outflow style models to explain the underluminous nature of Sgr A * . Second, on a scale of 5″ from Sgr A * , we detect new cometary radio and infrared sources at a position angle PA∼50°which is similar to that of two other cometary sources X3 and X7, all of which face Sgr A * . In addition, we detect a striking tower of radio emission at a PA∼50°-60°along the major axis of the Sgr A East supernova remnant shell on a scale of 150″ from Sgr A * . We suggest that the cometary sources and the tower feature are tracing interaction sites of a mildly relativistic jet from Sgr A * with the atmosphere of stars and the nonthermal Sgr A East shell at a PA∼50°-60°with´-, and opening angle 10°. Lastly, we suggest that the east-west ridge of radio emission traces an outflow that is potentially associated with past flaring activity from Sgr A * . The position angle of the outflow driven by flaring activity is close to −90°.

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The Proper Motion of Sagittarius A. II. The Mass of Sagittarius A

Cited by 759 publications

References 39 publications

An Improved Distance and Mass Estimate for SGR A* From a Multistar Orbit Analysis

An Improved Distance and Mass Estimate for SGR A* From a Multistar Orbit Analysis

The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution

SGR A* and Its Environment: Low-Mass Star Formation, the Origin of X-Ray Gas and Collimated Outflow

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