A VLA survey for compact radio sources in the galactic center

The scattering diameters of Sgr A* and several nearby OH masers (approximate to 100 at 1 GHz) indicate that a region of enhanced scattering is along the line of sight to the Galactic center. This region of enhanced scattering implies that radio pulsars in or beyond the Galactic center will suffer pulse broadening of hundreds of seconds at 1 GHz. We have used the VLA at 1.4 GHz to survey the inner 2 of the Galactic center for radio pulsar candidates. Because of the large pulse broadening suffered by Galactic center radio pulsars, our strategy has been to identify compact radio sources, without regard to whether they are pulsed radio sources. We describe our survey and present the catalog of 170 sources. Comparison with other radio surveys of the area shows that just over half of these sources have not been detected previously; this same comparison reveals 29 sources that are not in higher frequency surveys, suggesting that the sources are either variable or steep spectrum, and a comparable number of sources in other surveys that should have been detected in this survey but were not. Comparison with infrared surveys shows that 59 (35%) sources have infrared counterparts and are likely to be H II regions. On the basis of the number of sources as yet unidentified, we estimate that there could have been no more than roughly 10(4)-10(5) supernovae in the past several million years in the Galactic center. This estimate is consistent with the number required to produce the X-ray-emitting plasma in the Galactic center and is marginally consistent with that required to explain the 1.8 MeVemission from Al-26.