High Frequency Radio Observations of PSR J1119-6127
Walid Majid (JPL, Caltech), Tatyana Dobreva (JPL, Caltech), Jonathon Kocz (JPL, Caltech), Joseph Lazio (JPL, Caltech), Jonas Lippuner (Caltech), Aaron Pearlman (JPL, Caltech), Thomas Prince (JPL, Caltech)
We have carried out a search for pulsed radio emission at 2 and 8 GHz from PSR J1119-6127, a young high-magnetic field radio pulsar situated in the supernova remnant SNR G292.2-0.5. This source has recently exhibited X-ray and gamma-ray bursts similar to those from Soft Gamma Repeaters (SGRs), as well as glitch behavior (see GCN Circular #19735, Atel #9274, and Atel#9284). Radio observations at L-band (1465 MHz) using the Parkes radio telescope over two days beginning 29 July 2016 have placed an upper limit of 90 uJy on flux density from this pulsar (Burgay et al., Atel #9286). Previous radio measurements, prior to the high energy outbursts, showed a typical radio flux of 1 mJy at L-band. We carried out two series of observations using the Deep Space Network (DSN) 70-m diameter radio dish in Canberra, Australia at center frequencies of 2.2 GHz (S-band) and 8.4 GHz (X-band), with a newly installed pulsar backend (PSRM). The observations were carried out on 31 July 2016 (31 minute duration starting at UT 23:41:12) and 1 August 2016 (3.5 hour duration starting at UT 23:37:12). Data were collected in filterbank search mode with frequency channel spacing of 1 MHz and time sampling of 512 us at 16 bits per sample We searched both datasets for evidence of pulsed emission near the spin period of the pulsar using an updated ephemeris provided by Archibald et al. (2016). We used both the standard periodicity search tools within the PRESTO pulsar software suite (http://www.cv.nrao.edu/~sransom/presto) and an FFA-based (fast folding algorithm) search method in the time domain around the nominal pulse period. We see no hint of pulsed emission at either S- or X-band. Using the calibration data and system configuration, we report upper limits of 0.14 mJy / 0.06 mJy for pulsed emission at S and X-bands respectively. The ATNF pulsar catalog lists a flux of 0.8/0.44 mJy 1.4 and 3 GHz respectively, yielding a relatively flat spectral index of -0.8. Using this spectral index, the expected flux at S and X bands before the X-ray outburst was 0.6/0.2 mJy respectively. We conclude that the pulsed emission at these higher frequencies are now suppressed by a factor of 3 or more at S- and X-bands post the SGR-like outburst event. We have also carried out a search for single pulses with widths up to 130 ms and have detected none above a SNR threshold of 6. We can place an upper limit of 45/20 mJy on bright single pulses at S- and X-bands respectively. While the radio pulsations seem to have ceased, as reported by Burgay et al. (Atel #9286), the Swift data shows strong pulsations at 0.4098626(1) s in the entire band (Antonopoulou et al., Atel #9282). Additional high frequency observations at several epochs after the outburst will be particularly informative given the strong dynamic radio emission typical of magnetars at high frequencies (S/X/K-bands). We thank the DSN team (Tom Kuiper and Carleen Ward) for their rapid response in scheduling the observations.
radio,x-ray,gamma ray,gamma-ray burst,magnetar,neutron star,pulsar,soft gamma-ray repeater,star,supernova remnant,supernovae,transient