THE PROPER MOTION OF THE GALACTIC CENTER PULSAR RELATIVE TO SAGITTARIUS A*
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Author(s)
Bower, Geoffrey C.
Deller, Adam
Demorest, Paul
Brunthaler, Andreas
Falcke, Heino
Moscibrodzka, Monika
O'Leary, Ryan M.
Eatough, Ralph P.
Kramer, Michael
Lee, K. J.
Date Issued
January 2015
Journal
The Astrophysical Journal
Publisher
IOP Publishing
Citation
Bower, Geoffrey C., Adam Deller, Paul Demorest, Andreas Brunthaler, Heino Falcke, Monika Moscibrodzka, Ryan M. O’Leary, et al. “THE PROPER MOTION OF THE GALACTIC CENTER PULSAR RELATIVE TO SAGITTARIUS A*.” The Astrophysical Journal 798, no. 2 (January 8, 2015): 120. © 2015 The American Astronomical Society
Version
Final published version
Abstract
We measure the proper motion of the pulsar PSR J1745-2900 relative to the Galactic center massive black hole, Sgr A*, using the Very Long Baseline Array (VLBA). The pulsar has a transverse velocity of 236 ± 11 km s[superscript –1] at position angle 22 ± 2 deg east of north at a projected separation of 0.097 pc from Sgr A*. Given the unknown radial velocity, this transverse velocity measurement does not conclusively prove that the pulsar is bound to Sgr A*; however, the probability of chance alignment is very small. We do show that the velocity and position are consistent with a bound orbit originating in the clockwise disk of massive stars orbiting Sgr A* and a natal velocity kick of [< over ~] 500 km s[superscript –1]. An origin among the isotropic stellar cluster is possible but less probable. If the pulsar remains radio-bright, multiyear astrometry of PSR J1745-2900 can detect its acceleration and determine the full three-dimensional orbit. We also demonstrate that PSR J1745-2900 exhibits the same angular broadening as Sgr A* over a wavelength range of 3.6 cm to 0.7 cm, further confirming that the two sources share the same interstellar scattering properties. Finally, we place the first limits on the presence of a wavelength-dependent shift in the position of Sgr A*, i.e., the core shift, one of the expected properties of optically thick jet emission. Our results for PSR J1745-2900 support the hypothesis that Galactic center pulsars will originate from the stellar disk and deepen the mystery regarding the small number of detected Galactic center pulsars.
MIT Department
Haystack Observatory
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DOI of Published Version
https://doi.org/10.1088/0004-637X/798/2/120
