MAXI/GSC detection of a new X-ray activity of high-mass X-ray binary pulsar, 2S 1553-542.

ATel #7018; M. Sugizaki, T. Mihara (RIKEN), H. Negoro (Nihon U.), S. Ueno, H. Tomida, S. Nakahira, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA), M. Morii, M. Serino, J. Sugimoto, T. Takagi, A. Yoshikawa, M. Matsuoka (RIKEN), N. Kawai, T. Yoshii, Y. Tachibana (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU), H. Tsunemi, D. Uchida (Osaka U.), M. Nakajima, K. Fukushima, T. Onodera, K. Suzuki, T. Namba, M. Fujita, F. Honda (Nihon U.), Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.), Y. Tsuboi, A. Kawagoe (Chuo U.), M. Yamauchi, Y. Morooka, D. Itoh (Miyazaki U.), K. Yamaoka (Nagoya U.) report on behalf of the MAXI team
on 3 Feb 2015; 03:37 UT
Credential Certification: Mutsumi Sugizaki (sugizaki@riken.jp)

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The MAX/GSC detected the increase of X-ray flux from the position consistent with the high mass X-ray binary pulsar, 2S 1553-542. The light curve indicates that the current activity started on around January 28 (MJD 57050) and the flux has been increasing gradually. The daily-average flux in the 2-20 keV band is ~0.06 photons cm^-2 s^-1 (20 mCrab) on February 2.

2S 1553-542 is a transient X-ray pulsar with 9.3 s period discovered by SAS-3 in 1975. The timing and spectral properties obtained from RXTE observations of the previous 2008 outburst, which lasted ~ 100 days, suggest that the source is a Be/X-ray binary with a very low-eccentricity orbit (e<0.09) (Pahari and Pal 2012, and reference therein). We encourage further multi-wavelength observations .

The MAXI light curves are placed at the following URL; http://maxi.riken.jp/top/index.php?cid=1&jname=J1557-544