MAXI/GSC detection of a hard-to-soft state transition in GX 339-4

ATel #16424; H. Negoro, M. Nakajima, K. Kobayashi, M. Tanaka, Y. Soejima, Y. Kudo (Nihon U.), T. Mihara, T. Kawamuro, S. Yamada, S. Wang, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU), Y. Tsuboi, S. Urabe, S. Nawa, N. Nemoto, E. Goto (Chuo U.), M. Shidatsu, Y. Niida (Ehime U.), I. Takahashi, M. Niwano, S. Sato, N. Higuchi, Y. Yatsu (Tokyo Tech), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, T. Kurihara (JAXA), Y. Ueda, K. Setoguchi, T. Yoshitake, Y. Nakatani, Y. Okada (Kyoto U.), M. Yamauchi, Y. Hagiwara, Y. Umeki, Y. Otsuki (Miyazaki U.), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC), and W. Iwakiri (Chiba U.)
on 30 Jan 2024; 04:41 UT
Credential Certification: Hitoshi Negoro (negoro@phys.cst.nihon-u.ac.jp)

Tweet

The MAXI/GSC detected a hard-to-soft state transition in GX 339-4, starting on January 25th, 2024. This outburst began in September, 2023 (ATel #16260), followed by a continuous X-ray flux increase (ATel #16302). Recently, Nyamai et al. also reported the continuous radio brightening at least until January 22th from MeerKAT observations (ATel #16421).

MAXI detected five bright outbursts from this source since 2009. The hard-to-soft transitions in the last three outbursts stared when 4-10 keV flux was at 200-300 mCrab, and this transition occurred at about 200 mCrab. Further brightening in the soft X-ray band is expected.


--------- For MAXI Mailing-List members -----------
We reported this transition through the MAXI "X-ray-star" mailing-list (ML No. 937) on January 29. A storage managing the MAXI ML crashed last year and some mail addresses of the ML members have been lost. If you, ML members, have not received the above mail-alert and/or "New-transient" mail-alerts on January 29. Please resubscribe the mailing-list: http://maxi.riken.jp/mailman/listinfo
We apologize for the inconvenience.

MAXI data for GX 339-4