XRISM/Xtend Transient Search (XTS) detected an X-ray flare possibly from a spectroscopic binary
ATel #16652; T. Yoshida, K. Fukushima, K. Hayashi, Y. Kanemaru, S. Ogawa (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), M. Nobukawa (NUE), K. Pottschmidt (UMBC, NASA GSFC, CRESST), M. Shidatsu (Ehime U.), Y. Terada (Saitama U.), Y. Terashima (Ehime U.), Y. Tsuboi (Chuo U.), H. Uchida (Kyoto U.), T. Yoneyama (Chuo U.), M. Yoshimoto (Osaka U.)
on 14 Jun 2024; 08:41 UT
Credential Certification: Tomokage Yoneyama (tyoneyama263@g.chuo-u.ac.jp)
Subjects: X-ray, Star, Transient, Variables
XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source candidate XRISM J1045-5954 on 2024-06-10 TT in the direction of the Carina Nebula. The source position is determined to be (R.A., Dec.) = (161.236 deg, -59.914 deg), with systematic error of ∼ 40 arcsec. The possible X-ray candidates are CXO GCN J104457.51-595429.5 and 4XMM J104457.5-595430. Each candidate is located ∼ 7 and 13 arcsec apart from the position of XRISM J1045-5954, respectively. The possible optical counterpart is Cl Collinder 228 113 (∼ 22 arcsec apart), which is a spectroscopic binary with the distance of ∼ 1.3 kpc.
The X-ray flare rose at 2024-06-10 13:23 TT with 90% error of 2 ks, peaked at 2024-06-10 17:08 TT with 90% error of 1 ks, and decayed with an e-folding time of 9.2 (+2.2/-1.8) × 103 sec (90% confidence level), which are derived by fitting the 0.4 – 10.0 keV light curve with a constant + burst model in the QDP software package.
The spectrum in the flare phase is reproduced with a thermal plasma (APEC) model with absorption of NH = 4.4 (+4.9/-4.2) × 1020cm-2 (90% confidence level) and temperature of kT = 2.7 (+0.8/-0.5) keV (90% confidence level). We obtain the model flux of 1.6 (+/-0.2) × 10-12 erg s-1cm-2 (0.4 – 10.0 keV). A systematic error of roughly 20% should be added to the statistical error. Corresponding luminosity is 3.3 (+/-0.4) × 10 32 erg s-1 by assuming the distance to XRISM J1045-5954 of 1.3 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.
