Pulsed Radio Emission from PSR J1119-6127 re-activated

ATel #9366; M. Burgay (INAF-OACagliari), A. Possenti (INAF-OACagliari), M. Kerr (CASS-ATNF-Marsfield), P. Esposito (U. Amsterdam), N. Rea (U. Amsterdam, CSIC-IEEC), F. Coti Zelati (U. Amsterdam, U. Insubria, INAF-OAB), G. L. Israel (INAF-OARoma) and S. Johnston (CASS-ATNF-Marsfield) on behalf of a larger collaboration
on 11 Aug 2016; 09:46 UT
Credential Certification: Andrea Possenti (possenti@oa-cagliari.inaf.it)

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Prompted by the disappearance of the pulsed radio emission from the known pulsar PSR J1119-6127 (Burgay et al., Atel #9286; Majid et al. Atel #9321), we have undertaken a program at the Parkes radio telescope to investigate any further evolution of the radio emission from the neutron star. In particular, since 29 July 2016 (i.e. starting about 40 hours after the first of the two SGR-like events shown by the source: Younes et al., GCN Circular #19735; Kennea et al., Atel #9274), several observations in search mode (with 256 MHz band-width, 256 us sampling, 4 bits, duration among 40 min to 60 min) were performed using the H-OH receiver and the PDFB backend at a central frequency of 1369 MHz. Calibration data were also collected immediately before each of these observations.

During an observation begun at UT 03:40:12 on 09 Aug 2016, a pulsed radio signal was detected by folding the data at the dispersion measure and the spin period of PSR J1119-6127 expected on the basis of the pre SGR-event radio ephemeris. An additional observation was then performed starting at UT 08:04:01 on 09 Aug 2016, which confirmed the re-appearance of the pulsed radio emission from the pulsar at L-band.

During these two integrations, the calibrated phased-averaged flux density of PSR J1119-6127 was significantly smaller than that typically observed prior the SGR-event (about 1 mJy). Moreover, in contrast with the relatively stable flux density previously reported for PSR J1119-6127, the source displayed variations of more than a factor 3, both over timescales of hours (ranging from about 0.2 mJy to about 0.7 mJy in 10 mins long sub-integrations, the uncertainty on the flux density being of order 15% for the faintest detections) and also over a timescale of order minutes only.

A timing solution including about eight years of data and a power-law model for timing noise variations was produced from the radio ToAs collected before and after the SGR burst, confirming the occurrence of a glitch of the same order of magnitude as the Archibald et al. result (Atel #9284 and arXiv:1608.01007v1).

Additional observations are planned in next days at Parkes to constrain better the parameters of the glitch and to investigate the preliminary indications of changes across the SGR-event both in the radio pulse profile and the polarization properties of the source. A parallel series of observations is ongoing in the gamma-ray and X-ray bands.

We thank Phil Edwards for promptly allocating the telescope time needed to monitor the radio properties of this target.