Radio pulsation and imaging study of SGR J1935+2154 with the uGMRT

ATel #13799; Mayuresh Surnis (JBCA, University of Manchester), Bhal Chandra Joshi (NCRA-TIFR), Manjari Bagchi (IMSc), Vishal Gajjar (UC Berkeley), Ketan R Sand (University of Delhi), Maura McLaughlin (WVU), Duncan Lorimer (WVU), Harsha Blumer (WVU), Benetge Perera (Arecibo Observatory), P. K. Manoharan (Arecibo Observatory), Benjamin Stappers (JBCA, University of Manchester)
on 10 Jun 2020; 23:31 UT
Credential Certification: Mayuresh Surnis (msurnis@gmail.com)

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Following a series of recent X-ray bursts (Palmer et al., ATEL #13675; Younes et al., ATEL #13678) and the subsequent radio detection of millisecond duration radio bursts with CHIME (Scholz et al., ATEL #13681), STARE2 (Bochenek et al., ATEL #13684) and FAST (Zhang et al., ATEL # 13699), we observed SGR J1935+2154 with the Arecibo Observatory (AO), Green Bank Telescope (GBT) and upgraded Giant Metrewave Radio Telescope (uGMRT) at six epochs. We have already reported non-detections from five epochs (Surnis at al., ATEL #13769, ATEL #13777). Here we report the results from the analysis of the band-5 beamformed data (as mentioned in Surnis et al., ATEL #13777) and the last epoch of the uGMRT observations. These observations were carried out with the band-3 (300-500 MHz) on 2020 June 8, 23:30 UT for an on-source time of about two hours. We observed the nearby millisecond pulsar PSR B1937+21 as a test pulsar.

We made radio images of the associated supernova remnant (SNR) G057.2+00.8 with a synthesized beam size of about 5.4" * 7.9" with a beam position angle of 82 degree. We do not detect any continuum emission at the position of the magnetar with 3 sigma flux density upper limit of 465 microJy at 0.4 GHz.

We also carried out harmonic and single-pulse search on the beamformed data resulting in non-detection of any significant radio emission. The 10 sigma upper limits for the fluence of the single-pulse emission with a pulse width of 1 ms are 0.26 and 0.55 Jy ms at 1.36 and 0.4 GHz, respectively. The 10 sigma upper limits for the regular pulsed emission for a duty cycle of 10% are 26 and 66 microJy at 1.36 and 0.4 GHz, respectively.

We detected a few strong single-pulses from PSR B1937+21 in the band-3 beamformed data. These pulses along with the SNR images are available at the link below.

We thank the staff of the GMRT who have made these observations possible. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research.

Radio images of the SNR and single-pulse detections from PSR B1937+21