Search for pulsed radio emission from PSR J1745-2900 at 1 GHz with the GMRT

ATel #5070; M. P. Surnis, B. C. Joshi, S. Roy (National Centre for Radio Astrophysics, Pune, India)
on 17 May 2013; 17:48 UT
Credential Certification: Bhal Chandra Joshi (bcj@ncra.tifr.res.in)

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We have observed, with the GMRT, PSR J1745-2900, which was discovered following an X-ray flare by Swift, accompanied by 35-ms flare (ATEL #5006, #5009). Pulsating high energy and radio emission with a period of 3.76 s have been subsequently reported with emission properties and estimated surface magnetic field consistent with a magnetar (ATEL #5020, #5032, #5035, #5040, #5043, #5046, #5053, #5058). The observations were carried out at the source position provided in ATEL #5032 with 14 antenna of the GMRT used as a phased array at 1041 GHz. Data from 512 channels across 33.33333 MHz band were recorded with a sampling time of 1 ms on 2013-05-09 at 22:52:19 UTC for 1.0 hours. The data were incoherently dedispersed to 476 trial DMs ranging from 0 - 2000 pc cm^-3 followed by a harmonic and single pulse search. No significant radio pulsations were detected. We estimate an upper limit on flux density of 0.4 mJy for 30% duty cycle (system temperature ~ 140 K - Treceiver 70K and Tsky 70 K). We estimate an upper limit of 37 mJy for individual bursts. Our non-detection is consistent with high scatter-broadening for the pulsar implying a large DM. Thus, the pulsar is unlikely to be detected at frequencies lower than 1 GHz. Further, we do not find any other pulsar candidate at low DM (< 100 pc cm^-3). Strong RRAT like bursts, useful to constrain scatter-broadening, may be detectable, but we do not detect such bursts in our observations. The field was imaged using 22 antennas of the GMRT simultaneously with the time-series observations. The source lies within ~1 synthesised beamwidth away from Sgr A*. Due to very high confusion from Sgr A* at its vicinity at our waveband, we cannot put an upper limit on its continuum flux density.