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High Frequency Radio Observations of the Reactivated Magnetar PSR J1622-4950

ATel #10581; Aaron B. Pearlman (Caltech, JPL), Walid A. Majid (JPL, Caltech), Thomas A. Prince (Caltech, JPL), Shinji Horiuchi (CSIRO), Jonathon Kocz (Caltech), T. J. W. Lazio (JPL,, Caltech), Charles J. Naudet (JPL, Caltech)
on 18 Jul 2017; 18:00 UT
Credential Certification: Walid Majid (majidw@gmail.com)

Subjects: Radio, X-ray, Neutron Star, Pulsar, Magnetar

Radio emission from the magnetar PSR J1622-4950 was recently reported to have resumed (Camilo et al., ATel #10346). We have carried out Target of Opportunity (ToO) radio observations of PSR J1622-4950 at S-band (2.3 GHz) and X-band (8.4 GHz) using the 70-m diameter Deep Space Network (DSN) radio dish (DSS-43) in Canberra, Australia. We report on our single polarization mode observations of PSR J1622-4950 spanning roughly 5 hours on 23 May 2017 starting at 16:03:32 UTC.

Pulsations were detected at a period of 4.327308(1) s. We measure a mean flux density of 3.8(8)/0.41(8) mJy at S/X-band, from which we derive a spectral index of -1.7(2). We note that PSR J1622-4950's spectral behavior is now consistent with the majority of pulsars, which have a mean spectral index of -1.8(2) (Maron et al. (2000)). The result by Maron et al. (2000) is used here because they included more high frequency pulsar spectra than other studies to characterize the underlying spectral index distribution over a wide frequency range.

The mean flux density at S-band has now increased by an order of magnitude compared to previous flux density measurements by Scholz et al. (2017) during the magnetar's quiescent state. Furthermore, the spectral index has steepened compared to a nearly flat spectral index from flux density measurements between 1.4 and 24 GHz prior to the disappearance of the radio emission (Levin et al. (2010); Keith et al. (2011); Levin et al. (2012); Anderson et al. (2012); Scholz et al. (2017)).

We are continuing to monitor changes in PSR J1622-4950's radio spectrum at both S-band and X-band. We thank the DSN (Deep Space Network) and Canberra Deep Space Communication Complex (CDSCC) teams for scheduling these observations.