SRG observations of SGR 1935+2154: four days prior to the FRB event
ATel #13723; Medvedev P. S. (1), Sunyaev R. A. (1, 2), Gilfanov M. R. (1, 2), Lutovinov A. A. (1), Molkov S. V. (1), Semena A. N. (1), Pavlinsky M. N. (1), Mereminskiy I. A. (1), Khabibullin I. I. (1, 2) (1: IKI RAS, Moscow; 2: MPA, Garching)
on 9 May 2020; 15:22 UT
Credential Certification: Ilya Mereminskiy (i.a.mereminskiy@gmail.com)
Subjects: X-ray, Neutron Star, Magnetar
The well-known Galactic magnetar SGR 1935+2154 which recently had
shown a millisecond time-scale radio burst (see ATel #13681) was in the scan path
of SRG observatory on 23-24 Apr 2020, four days prior to detection of
the radio flare and three days before start of the bursting activity
in X-ray band (ATel #13675).
The SGR 1935+2154 position was scanned by SRG/eRosita telescope 5 times
with the total effective exposure of 140 sec. The
source was detected by eRosita in the soft band with the
flux of (2.3 +/- 0.5) x 10^-13 ergs/cm^2/s and (8.7 +/- 0.5) x 10^-13
ergs/cm^2/s in the 0.3-2.0 keV and 2-4 keV bands (68% confidence).
No statistically significant variability was found over the period of
observations.
SRG/ART-XC telescope observed the source with the effective exposure of 25
sec and obtained an upper limit of 7.5 x 10^-12 ergs/cm^2/s in the
4-12 keV band.
The 0.3-4.0 keV spectrum of the source can be described with a power
law spectrum with photon index of Gamma=1.5 +/- 0.6 or
a black body spectrum with temperature of kT=0.6+/-0.2 keV (absorption
fixed at the value NH =2 x 10^22 cm-3).
