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Title: THE PROPER MOTION OF THE GALACTIC CENTER PULSAR RELATIVE TO SAGITTARIUS A*

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{sup –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 ≲ 500 km s{sup –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 inmore » 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.« less
Authors:
 [1] ; ;  [2] ;  [3] ; ; ; ; ; ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9]
  1. Academia Sinica Institute of Astronomy and Astrophysics, 645 N. A'ohoku Place, Hilo, HI 96720 (United States)
  2. ASTRON, PO Box 2, 7990 AA Dwingeloo (Netherlands)
  3. NRAO, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States)
  4. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
  5. Department of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University, PO Box 9010, 6500 GL Nijmegen (Netherlands)
  6. JILA, University of Colorado and NIST, 440 UCB, Boulder, CO 80309-0440 (United States)
  7. Department of Physics, Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom)
  8. MIT Haystack Observatory, Route 40, Westford, MA 01886 (United States)
  9. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22364602
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 798; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; BLACK HOLES; JETS; MILKY WAY; ORBITS; ORIGIN; PROBABILITY; PROPER MOTION; PULSARS; RADIAL VELOCITY; SCATTERING; STARS; THREE-DIMENSIONAL CALCULATIONS; WAVELENGTHS