The Neil Gehrels Swift Observatory detection of hard X-ray outburst from Cygnus X-3
ATel #14298; Sabyasachi Pal (MCC/ICSP), Bikram Bhunia (MCC), Manoj Mandal (MCC), Debasish Saha (MCC) and Mangal Hazra (MCC)
on 1 Jan 2021; 20:41 UT
Credential Certification: Sabyasachi Pal (sabya.pal@gmail.com)
Subjects: X-ray, Request for Observations, Black Hole, Transient
Referred to by ATel #: 14397
We report the detection of new hard X-ray outburst from Cygnus X-3 using the Burst Alert Telescope (BAT) on the Neil Gehrels Swift Observatory. The BAT flux (15-50 keV) reached 0.24 Crab (0.054±0.003 counts/cm2/sec) on MJD 59213 (30th December 2020) which is highest since the outburst of the source in October 2019. Cygnus X-3 is one of the brightest X-ray and radio sources in the Galaxy. Earlier, the source showed multiple flaring activities in radio and X-ray wavelengths (eg., ATel #809, #1100, #1486, #1881, #13835 etc.).
The source did not show significant variation in soft X-ray. We also study the present flare of Cygnus X-3 using MAXI/GSC. On 59210 (27th December 2020), the 1 day averaged X-ray flux in 2-20 keV and 4-10 keV were 0.13±0.009 Crab and 0.053±0.004 Crab respectively. The flux of the source at soft X-ray range (2-20 keV, observed by MAXI), is comparatively weak than flux measured in hard X-ray range (15-50 keV, observed by SWIFT/BAT). We also look for the variation of hardness ratio using MAXI/GSC and SWIFT/BAT. The hardness ratio in MAXI/GSC energy band (4-10 kev/2-4 keV) varies between 1.2-2.4 during 59200-59211 MJD. The hardness ratio BAT (15-50 keV)/MAXI (2-20 keV) has started to increase from ~0.7 on MJD 59200 and reached to ~2.6 on MJD 59211.
Further observations in all wavelengths are encouraged.
This research has made use of MAXI data provided by RIKEN, JAXA and the MAXI team.
