A NEW RADIO DETECTION OF THE TRANSIENT BURSTING SOURCE GCRT J1745-3009

摘要

GCRT J1745-3009 is a transient bursting radio source located in the direction of the Galactic center, discovered by Hyman et al. in 330 MHz VLA observations from 2002 September 30-October 1. We have searched for bursting activity from GCRT J1745-3009 in nearly all of the available 330 MHz VLA observations of the Galactic center since 1989, as well as in 2003 Giant Metrewave Radio Telescope (GMRT) observations. We report a new radio detection of the source in 330 MHz GMRT data taken on 2003 September 28. Due to sparse sampling of the observation, only a single burst, already at or passed its peak, was detected. The maximum flux density detected was ～0.5 Jy, approximately 3 times weaker than the five bursts detected in 2002. We present tentative evidence suggesting that this burst is an isolated one, but we cannot rule out additional undetected bursts that may have occurred with the same ～77 minute periodicity observed in 2002 or with a different periodicity. Assuming the peak emission was detected, the decay time of the burst, ～2 minutes, is consistent with that determined for the 2002 bursts. Based on the total time for which we have observations, we estimate that the source exhibits bursting activity roughly 9% of the time.