Searches for Dispersed Radio Pulsar Emission from the Sag A* SGR

ATel #5033; C. G. Bassa, C. A. Jordan, E. F. Keane, A. G. Lyne, B. W. Stappers & P. Weltevrede (Jodrell Bank Centre for Astrophysics, Manchester, UK).
on 1 May 2013; 07:31 UT
Credential Certification: Evan Keane (ekean@jb.man.ac.uk)

Tweet

We report on a search for radio pulsations at the 3.76-s period found by Mori et al. (ATEL #5020) of the magnetar towards Sgr A*. The 76-m Lovell radio telescope at Jodrell Bank observed the XRT position (Kennea et al. ATEL #5009) from 03:30UT to 04:30UT on April 27, 2013. Raw voltages of two orthogonal polarisations over 400 MHz of bandwidth at L-band (1332 to 1732MHz) were Nyquist sampled, digitised at 8 bits and recorded to disk. The raw voltages were coherently dedispersed to a trial dispersion measure of 1000 pc cm^-3 and folded at the 3.76-s period. The data were subsequently incoherently dedispersed with trials up to a dispersion measure of 3000 pc cm^-3, with a maximum dispersive smearing due to channelisation of 4.6 ms. No radio pulsations were detected. We furthermore performed a search for individual bursts over the same range in dispersion measure; no events were found. Another observation, folded at the pulse period, was obtained at 01:50UT to 02:50UT on April 28, 2013 and produced the same results.

During these observations the source was at an elevation of ~8 degrees, increasing the system temperature due to spillover by 30 K, to a total of 76 K (receiver + spillover + sky). Assuming a 10% duty cycle, we estimate an upper limit on the flux density of a periodic signal of 0.21 mJy at 1532 MHz for an effective bandwidth of 300 MHz. In the case of an individual burst we estimate an upper limit of 30 mJy.