MAXI/GSC detection of X-ray brightening from the X-ray pulsar XTE J1946+274

ATel #14936; M. Nakajima, H. Negoro (Nihon U.), T. Mihara (RIKEN), M. Sugizaki (NAOC), R. Uematsu (Kyoto U.), K. Kobayashi, K. Asakura, K. Seino (Nihon U.), T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, K. Komachi, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, H. Kawai, Y. Okamoto, S. Kitakoga (Chuo U.), M. Shidatsu (Ehime U.), N. Kawai, M. Niwano, R. Hosokawa (Tokyo Tech), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, M. Tominaga, T. Nagatsuka, T. Omama, M. Kurihara (JAXA), Y. Ueda, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake, Y. Goto (Kyoto U.), H. Tsunemi (Osaka U.), M. Yamauchi, Y. Nonaka, T. Sato, R. Hatsuda, R. Fukuoka (Miyazaki U.), T. Kawamuro (UDP/NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU),
on 24 Sep 2021; 15:18 UT
Credential Certification: Motoki Nakajima (nakajima.motoki@nihon-u.ac.jp)

Tweet

On 2021-09-23 (MJD 59480), the MAXI/GSC nova alert system triggered on X-ray brightening from the source positionally consistent with the transient Be/X-ray binary pulsar XTE J1946+274. A preliminary analysis reveals that this outburst started from 2021-09-20 (MJD 59477), and the 4-10 keV flux binned at 0.25 days centered on 2021-09-23.583 (MJD 59480.584) reached 0.083 ± 0.023 photons/s/cm² (66 ± 18 mCrab). The onset phase of the current brightening is ∼ 0.95 (P_orb=172.7 d and T_peri=55514.8(MJD); Marcu-Cheatham et al. 2015). This is the fourth detection of a series of X-ray activities from this source since its discovery in 1998 (Wilson et al. 1998, Smith \& Takeshima 1998).

The source light curves can be checked at the following pages;
MAXI(http://maxi.riken.jp/pubdata/v7l/J1945+273/index.html),
Swift/BAT(https://swift.gsfc.nasa.gov/results/transients/weak/XTEJ1946p274/),
Fermi/GBM(https://gammaray.nsstc.nasa.gov/gbm/science/pulsars/lightcurves/xtej1946.html), and
the BeXRB monitor page(http://integral.esac.esa.int/bexrbmonitor/webpage_oneplot.php).