XRISM/Xtend Transient Search (XTS) detected a possible stellar flare from 2MASS J11414215-6521298
ATel #16774; S. Ogawa, K. Fukushima, K. Hayashi, Y. Kanemaru, 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), 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. Yanagi (Chuo U.), T. Yoneyama (Chuo U.), M. Yoshimoto (Osaka U.)
on 15 Aug 2024; 04:32 UT
Credential Certification: Tomokage Yoneyama (tyoneyama263@g.chuo-u.ac.jp)
Subjects: X-ray, Star, Transient
XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1142-6522 on 2024-08-13 TT. The source position is determined to be (R.A., Dec.) = (175.418, -65.363), with a systematic error of – 40 arcsec. The plausible counterpart is 2MASS J11414215-6521298, a young stellar object candidate with a distance of – 101 pc. 2MASS J11414215-6521298 is located – 20 arcsec apart from the position of XRISM J1142-6522.
Due to a bad time interval of XRISM, the intrinsic flare peak may not be detected, but a rough constraint, 2024-08-13 02:43 – 04:25 TT is given for the flare peak time. The flare exponentially decayed with an e-folding time of 2.5 (+1.2/-1.0) × 103 sec (90% confidence level), which is derived by fitting the 0.4 – 10.0 keV light curve with a constant + exponential model in the QDP software package.
In order to estimate the source flux, we fit the spectrum in the flare peak phase with absorbed APEC model with temperatures of kT = 0.69 (+0.20/-0.25) keV (90% confidence level) and hydrogen column density nh = 5.2 (+2.0/-2.4) × 1021 cm-2 (90% confidence level). Then, the model flux is calculated as 1.4 (+0.3/-0.3) × 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 1.8 (+0.3/-0.3) × 10 30 erg s-1 by assuming the distance to 2MASS J11414215-6521298 of 101 pc.
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.
