MAXI/GSC detection of the onset of new X-ray outburst from the X-ray pulsar XTE J1946+274
ATel #16717; M. Nakajima (Nihon U.), T. Mihara (RIKEN), H. Negoro, Y. Kudo, H. Shibui, K. Takagi, H. Takahashi, K. Tatano, H. Nishio (Nihon U.), T. Kawamuro, S. Yamada, S. Wang, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, Y. Kawakubo, H. Hiramatsu, H. Nishikawa, Y. Kondo, A. Yoshida (AGU), Y. Tsuboi, H. Sugai, N. Nagashima (Chuo U.), M. Shidatsu, Y. Niida (Ehime U.), I. Takahashi, M. Niwano, N. Higuchi, Y. Yatsu (Tokyo Tech), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, M. Kurihara (JAXA), Y. Ueda, Y. Okada (Kyoto U.), M. Yamauchi, Y. Otsuki, T. Hasegawa, M. Nishio (Miyazaki U.), K. Yamaoka (Nagoya U.), M. Sugizaki (Kanazawa U.), W. Iwakiri (Chiba U.)
on 18 Jul 2024; 13:38 UT
Credential Certification: Motoki Nakajima (nakajima.motoki@nihon-u.ac.jp)
Subjects: X-ray, Binary, Neutron Star, Transient, Pulsar
On 2024-07-17 (MJD 60508), the MAXI/GSC nova alert system triggered a faint X-ray activity from the source positionally consistent with the transient Be/X-ray binary pulsar XTE J1946+274. The current brightening started from 2024-07-14 (MJD 60505), or the orbital phase of ∼0.9 which is calculated with the orbital ephemerisis determined by Marcu-Cheatham et al. 2015 (Porb=172.7 d and Tperi=55514.8(MJD). The 4-10 keV flux is increasing with the average rate of 0.08 photons/s/cm2/day (or ∼7mCrab/day). The previous X-ray outburst from this source was reported in 2021 (ATel#14936). If the present outburst traces the last X-ray activity, the X-ray flux will reach the maximum within ∼10 days.
The latest source light curves can be checked at the following pages;
MAXI ( http://maxi.riken.jp/pubdata/v7.7l/J1945+273/index.html ),
Swift/BAT ( https://swift.gsfc.nasa.gov/results/transients/weak/XTEJ1946p274/ ),
Fermi/GBM ( https://gammaray.msfc.nasa.gov/gbm/science/pulsars/lightcurves/xtej1946.html ), and
the BeXRB monitor page ( https://integral.esac.esa.int/bexrbmonitor/webpage_oneplot.php ).