Konus-Wind detection of a short X-ray burst coincident with a bright radio burst from SGR 1935+2154
ATel #15686; D. Frederiks, A. Ridnaia, D. Svinkin, A. Lysenko, M. Ulanov (all - Ioffe Institute), and A. Tsvetkova (Ioffe Institute/University of Cagliari)
on 16 Oct 2022; 15:51 UT
Credential Certification: Dmitry Frederiks (fred@mail.ioffe.ru)
Subjects: X-ray, Gamma Ray, Neutron Star, Soft Gamma-ray Repeater, Fast Radio Burst, Magnetar
Referred to by ATel #: 15698
Konus-Wind (KW) detected a short X-ray burst on 2022-10-14 in time interval from 19:21:39.205 UTC to 19:21:42.149 UTC. Corrected for the propagation from low-Earth orbit to Wind (~1.05 s), the burst arrival time is consistent with the detection time of a bright short X-ray burst from SGR 1935+2154,
reported by GECAM and HEBS (Atel #15682), which, in turn, is consistent with the dedispersed topocentric time of a bright radio burst detected from SGR 1935+2154 by CHIME (Atel #15681).
The event was detected by KW in the waiting mode and no detailed information on its temporal structure is available. The emission is seen in two instrument's energy bands: G1(20-80 keV) and G2 (80-320 keV), while no statistically significant signal is visible above 320 keV.
A time-averaged spectrum of the burst can be described in the 20-1300 keV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with the peak energy Ep of (40 ± 6) keV, which is slightly higher than a typical Ep of multiple bright SGR 1935+2154 bursts detected by KW recently (GCN Circ. 32768). We also note that the October 14 burst Ep is about twice as lower as the peak energy (~85 keV) measured by KW for the much radio-brighter event SGR/FRB200428 from the same magnetar (Ridnaia et al. 2021, NatAstr. 5, 372). From the KW detection, we estimate the total 20-500 keV fluence of the burst to (5.7 ± 0.6)x10^-7 erg/cm2, about two times lower than that of SGR/FRB200428.
