INTEGRAL/JEM-X detection of X-ray activity from V4641 Sgr
ATel #13547; I. Mereminskiy, S. Grebenev, R. Krivonos, R. Sunyaev (IKI RAS), J. Wilms (ECAP/FAU, Germany) and E. Kuulkers (ESA, The Netherlands) on behalf of the Galactic bulge monitoring team
on 10 Mar 2020; 16:00 UT
Credential Certification: Ilya Mereminskiy (i.a.mereminskiy@gmail.com)
Subjects: X-ray, Black Hole, Transient
Referred to by ATel #: 14968
V4641 Sgr is a peculiar black hole transient, that was shown to be in outburst in the beginning of 2020 (see ATel #13431, #13437). Although regular INTEGRAL observations of this field begun on February 8, the source was not detected in hard (>30 keV) X-rays by IBIS, nor in softer (3-20 keV) X-rays by JEM-X until March 6.
During the observations performed on March 6, JEM-X observed the source position for about 5 hours and found it to be active with a mean flux of 35±3 mCrab in the 3-12 keV band, corresponding to about 6x10-10 erg/cm2/s. The upper limit of the mean hard X-ray (30-60 keV) flux on March 5-7 is 5 mCrab (6x10-11 erg/cm2/s). This may indicate that the source still resides in the soft state, as was found in earlier observations by NuSTAR (ATel #13431) and NICER (ATel #13443).
INTEGRAL will continue to monitor the Galactic center region in upcoming revolutions and we encourage multiwavelength observations of this interesting source.
