XRISM follow-up observation of a new transient MAXI J1744-294 at the Galactic central region

ATel #17063; S. Mandel, K. Mori, C. Hailey (Columbia U.), M. Bachetti (INAF), N. Degenaar (U. Amsterdam), P. Draghis (MIT), J. Grindlay, J. Hong (Harvard CfA), G. Ponti (INAF, MPE), M. Reynolds (U. Michigan), J. Tomsick (UCB), R. Wijnands (U. Amsterdam), K. Fukushima, K. Hayashi, Y. Kanemaru, S. Ogawa, T. Yoshida, R. Iizuka (JAXA/ISAS), C. Baluta (NASA/GSFC), Y. Terada (Satama U.), E. Costantini (SRON), M. Guainazzi (ESA/ESTEC), R. Kelley (NASA/GSFC), K. Matsushita (TUS), R. Petre, B. Williams (NASA/GSFC), H. Yamaguchi, S. Watanabe (JAXA/ISAS), M. Tashiro (Saitama U.)
on 5 Mar 2025; 05:03 UT
Credential Certification: Kotaro Fukushima (kxfukushima@gmail.com)

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A follow-up XRISM observation has been performed for the new Galactic centre transient MAXI J1744-294 detected by MAXI on January 2, 2025 (ATels #16975 and #16983). This source was followed by NinjaSat on January 16-23 (ATel #17009), MeerKAT on January 25 (ATel #17045), Swift on January 14-16 and February 1 (ATel #17010), NuStar on February 6 (ATel #17031), and NICER on February 11-12 (ATel #17040) following the initial detection. Based on these reports, an unanticipated ToO request to XRISM for this target has been approved, and it started at 11:29UT on March 3, 2025, with 60 ks of exposure using the Director's Discretionary Time allocation of the observing cycle 1. All statistical uncertainties in this report will be provided as a 90% confidence level unless stated otherwise.

Two prominent sources are evidently detected around the aim point of the Xtend image extracted from the quick-look event data. The positions of the brighter and fainter sources are determined to be (R.A., Dec.) = (266.4179, -29.0127) and (266.3974, -29.0256), respectively. These estimates are with a systematic error of ∼ 40 arcsec. The brighter one appears at 18 arcsec, i.e., about 1 pc at 8.3 kpc, from the position of Sgr A*. We identify this source as the transient MAXI J1744-294. The fainter one may be a low-mass X-ray binary AX J1745.6-2901.

A preliminary spectral analysis on the Resolve data shows that the emission can be reproduced with a steep power-law Γ = 2.797 +/- 0.006 and a kT_in = (0.6344 +/- 0.0011) keV diskbb in the energy range 1.9–12 keV with a strong absorption (1.23 +/- 0.04) × 10²³ cm^-2. The obtained absorbed flux is (8.518 +/- 0.017) × 10^-10 erg s^-1cm^-2 in 2–10 keV, corresponding to the luminosity of (7.023 +/- 0.014) D²_8.3kpc × 10³⁶ erg s^-1. While we do not take a pile-up effect into account at this moment, the derived X-ray flux is still comparable to the previously reported values (ATels #16975, #16983, #17009, #17010, #17031, and #17040).

Follow-up monitors are encouraged.