Radio Pulsars in the Galactic Center

Joseph Lazio1, James Cordes2, Cornelia Lang3, Eric Gotthelf4

1 Naval Research Laboratory, Code 7213, 4555 Overlook Ave. SW, Washington, DC 20375-5351 USA
2 Dept. of Astronomy, Cornell University and National Astronomy & Ionosphere Center, Ithaca, NY 14853-6801 USA
3 Dept. of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 USA
4 Columbia Astrophysics Lab, Columbia University, 550 W. 120 th Street, New York, NY 10027 USA

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See: ApJ, 475, 557 (1997)

Radio pulsars in the Galactic center would serve as useful probes of its magnetoionic medium, and possibly its spacetime structure. However, of the roughly 1200 known pulsars, no more than 1% are within 1 degree of Sgr A* and none have distances consistent with being within or behind the Galactic center. This deficit of pulsars is due to interstellar scattering so severe as to smear together individual pulses.

We are engaged in a radio survey using the VLA to find compact radio sources at 1.4 GHz. The objective is to identify sources on which a periodicity search can be conducted at frequencies high enough to defeat the interstellar pulse broadening (> 10 GHz). By cross-correlation with other radio surveys of the Galactic center, we have found roughly 10 sources that appear to be promising radio pulsars. We are pursuing periodicity searches of these objects on the 100 m Efflesberg and Green Bank Telescopes. By cross-correlation with the Chandra X-ray survey of the Galactic center, we have also discovered an enigmatic point source.

Basic research in radio astronomy at the NRL is supported by the Office of Naval Research.