GBT detection of bright 5 GHz radio bursts from SGR 1935+2154, coincident with X-ray and 600 MHz bursts
ATel #15697; Yogesh Maan (NCRA - TIFR, India), Joeri van Leeuwen (ASTRON, NL), Samayra Straal (NYU Abu Dhabi, UAE) and Ines Pastor-Marazuela (UvA, NL)
on 19 Oct 2022; 13:45 UT
Credential Certification: Yogesh Maan (maan@astron.nl)
Subjects: Radio, X-ray, Neutron Star, Soft Gamma-ray Repeater, Transient, Magnetar
Triggered by recent X-ray activity (GCN #32675, ATel #15667, #15672), we observed SGR 1935+2154 with the Green Bank Telescope (GBT) on 2022 Oct 14. During a C-Band session, we detected at least 5 bursts with high signal to noise ratio. All these bursts were detected within a time span of 1.5 seconds, i.e., well within one rotation of the magnetar, but over a range of phases. Throughout the entire duration of the two brightest bursts, the receiver system is clearly strongly saturated.
The two brightest bursts occurred around 2022-10-14T19:21:39.1 UTC (topocentric, infinite frequency arrival time), consistent with the reported trigger time of a short (about 250 ms wide) bright X-ray burst detected by GECAM-B and GECAM-C (ATEL #15682). The CHIME/FRB burst at 600 MHz is consistent with any of these bursts within the arrival time precision reported in ATel #15681.
Most bursts cover the entire 4.2-5.6 GHz band, representing the highest-frequency radio detections of SGR 1935+2154 to date. The magnetar thus emits over more than a factor 10 in radio bandwidth, from CHIME/FRB at 400 MHz to our detections up to 5.6 GHz. Most bursts also exhibit fine temporal substructures.
We will report on the fluence of the two brightest bursts, and hence the burst radio spectrum, once we quantify the saturation response of the receiver system. Further analysis of the bursts is also underway, as is continued monitoring.
We thank the Green Bank Observatory and staff for the prompt scheduling of our triggered observations and their support.
