XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an eclipsing binary
ATel #17144; Y. Ishihara (Chuo U.), K. Fukushima, Y. Kanemaru, S. Ogawa (JAXA), M. Audard (U. de Geneve), E. Behar (Technion), S. Inoue (Kyoto 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. Yoneyama (Chuo U.), M. Yoshimoto (Ehime U.)
on 14 Apr 2025; 11:24 UT
Credential Certification: Tomokage Yoneyama (tyoneyama263@g.chuo-u.ac.jp)
Subjects: X-ray, Binary, Star, Transient, Variables
XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1746-2940 on 2025-04-12 TT. The source position is determined to be (R.A., Dec.) = (266.528, -29.671), with a systematic error of ~ 40 arcsec. A plausible counterpart is an eclipsing binary V734 Sgr located ~ 10 arcsec apart from the position of XRISM J1746-2940.
The flare started at 2025-04-12 at ~ 12:38 TT. The flare reached its peak on 2025-04-12 at ~ 13:12. The flare exponentially decayed in 104 sec.
The peak flux is estimated to be 2 × 10-11 erg s-1 cm-2 (0.4 – 10.0 keV). A systematic error of roughly 20% should be added to the statistical error. Corresponding luminosity is 2 × D978pc × 1033 erg s-1 by assuming the distance to XRISM J1746-2940 of D978pc.
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.
