XRISM/Xtend Transient Search (XTS) reported the third detection of a prestellar flare from 2MASS J11414215-6521298
ATel #16777; 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 16 Aug 2024; 11:11 UT
Credential Certification: Tomokage Yoneyama (tyoneyama263@g.chuo-u.ac.jp)
Subjects: X-ray, Star, Transient, Young Stellar Object
XRISM/Xtend Transient Search (XTS) detected X-ray flares from the X-ray source XRISM J1142-6522, whose possible counterpart is 2MASS J11414215-6521298 at 101 pc, on 2024-08-15 TT. We report the largest flare in this period although the activity is continued. This is XRISM's third report on a brightening of this source following the last ones (ATel #16774 and #16775). The source position is (R.A., Dec.) = (175.418, -65.363), with a systematic error of ∼ 40 arcsec. As described below, this prestellar flare is by factors of 28 and 4 brighter than the ones reported in ATels #16774 and #16775, respectively. All statistical uncertainties in this report will be provided as a 90% confidence level unless stated otherwise.
Despite rough constraints due to a bad time interval of XRISM, the start and peak times of this flare would have been 2024-08-15 04:08 – 04:45 TT and 2024-08-15 05:22 – 05:33 TT, respectively. The decay time of the largest flare cannot be constrained firmly since another big one occurred during this brightening. The interval between this flare and the last one (ATel #16775) is about 24 hours, which is in plausible agreement with the interval between the last brightening and the one before that (ATel #16774).
In order to calculate the source flux, we fit the spectrum in the flare peak phase with an unabsorbed APEC model with a temperature of kT = 5.5 (+1.1/-0.8) keV. Then, the model flux was estimated to be 4.1 (+0.3/-0.3) × 10-11 erg s-1cm-2 (0.4 – 10.0 keV). A systematic error of roughly 20% should be added to statistical errors of the flux. Corresponding luminosity is 5.1 (+0.3/-0.3) × 10 31 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.
