XRISM/Xtend Transient Search (XTS) detected an X-ray flare at the galactic center
ATel #17092; T. Yoneyama (Chuo U.), K. Fukushima, K. Hayashi, Y. Kanemaru, S. Ogawa, T. Yoshida (JAXA), M. Audard (U. de Geneve), E. Behar (Technion), S. Inoue (Kyoto U.), Y. Ishihara (Chuo U.), T. Kohmura (TUS), Y. Maeda (JAXA), M. Mizumoto (UTEF), N. Nagashima (Chuo U.), M. Nobukawa (NUE), K. Pottschmidt (UMBC, NASA GSFC, CRESST), M. Shidatsu (Ehime U.), H. Sugai (Chuo U.), Y. Terada (Saitama U.), Y. Terashima (Ehime U.), Y. Tsuboi (Chuo U.), H. Uchida (Kyoto U.), T. Yanagi (Chuo U.),, M. Yoshimoto (Osaka U.)
on 20 Mar 2025; 16:23 UT
Credential Certification: Tomokage Yoneyama (tyoneyama263@g.chuo-u.ac.jp)
Subjects: X-ray, Transient, Variables, Young Stellar Object
XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1747-2832 located at the Galactic central region on 2025-03-19 TT. The source position is determined to be (R.A., Dec.) = (266.761, -28.538), with a systematic error of ∼ 40 arcsec. There are many objects around XRISM J1747-2832, including three YSO candidates and a molecular cloud, NAME Sgr B1, which is located ∼ 9 asec apart from the position of XRISM J1747-2832. We then suggest that a YSO is the origin of the X-ray flare.
The flare started on 2025-03-19T08:09 TT, peaked at 09:08 TT and then exponentially decayed in ∼ 3 ksec, which is derived by fitting the 0.4 – 2.0 keV light curve with a constant + burst model in the QDP software package.
In order to estimate the source flux, we fit the spectrum in the flare phase with an absorbed APEC model. Due to the low statistics, we only obtain a lower limit of the temperature of kT > 1.4 keV and an upper limit of the hydrogen column density NH < 1 × 1022 cm-2. The flux is estimated as 2 × 10-12 erg s-1 cm-2 (0.4 – 10.0 keV). A systematic error of roughly 20% should be added to the statistical error. Although the distance to XRISM J1747-2832 is unknown, corresponding luminosity is estimated as 2 D21 kpc × 10 32 erg s-1 if we assume the distance of 1 kpc.
We derived the above systematic error for the flux by comparing our derived values for the sources detected with XTS in several observations with those for the corresponding X-ray counterparts. We estimated the systematic error for the source position from the separations between the detected sources with the corresponding counterparts in the same field of view.
