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

Journal Article · Sat Jan 10 00:00:00 EST 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/798/2/120· OSTI ID:22364602

Bower, Geoffrey C. ^[1]; Deller, Adam; Falcke, Heino ^[2]; Demorest, Paul ^[3]; Brunthaler, Andreas; Eatough, Ralph P.; Kramer, Michael; Lee, K. J.; Spitler, Laura; Desvignes, Gregory ^[4]; Moscibrodzka, Monika ^[5]; O'Leary, Ryan M. ^[6]; Rushton, Anthony P. ^[7]; Doeleman, Sheperd ^[8]

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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)

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 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.

• OSTI ID: 22364602
• Journal Information: Astrophysical Journal, Vol. 798, Issue 2; 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
ACCELERATION
BLACK HOLES
JETS
MILKY WAY
ORBITS
ORIGIN
PROBABILITY
PROPER MOTION
PULSARS
RADIAL VELOCITY
SCATTERING
STARS
THREE-DIMENSIONAL CALCULATIONS
WAVELENGTHS