MAXI/GSC detection of a bright X-ray burst from XTE J1701-407
ATel #12617; W. Iwakiri(Chuo U.), M. Serino(AGU), S. Nakahira(RIKEN), H. Negoro(Nihon U.), K. Gendreau, Z. Arzoumanian, P. Bult, E. Ferrara(NASA/GSFC), M. Nakajima, A. Sakamaki, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), T. Mihara, F. Yatabe, Y. Takao, M. Matsuoka (RIKEN), T. Sakamoto, S. Sugita, T. Hashimoto, A. Yoshida (AGU), N. Kawai, M. Sugizaki, Y. Tachibana, K. Morita, M. Oeda, K. Shiraishi (Tokyo Tech), S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai, T. Midooka (JAXA), Y. Ueda, A. Tanimoto, T. Morita, S. Yamada, S. Ogawa (Kyoto U.), Y. Tsuboi, R. Sasaki, H. Kawai, T. Sato (Chuo U.), H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.), M. Yamauchi, K. Hidaka, S. Iwahori, Y. Kurihara(Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), M. Shidatsu (Ehime U.), Y. Kawakubo (LSU) report on behalf of the MAXI team and NICER team:
on 1 Apr 2019; 03:42 UT
Credential Certification: Wataru Iwakiri (wataru.iwakiri@riken.jp)
Subjects: X-ray, Binary, Neutron Star, Transient
We report the MAXI/GSC detection of a bright X-ray burst from LMXB XTE J1701-407 and the results of the follow-up observations of NICER which started at about 3 hours after the MAXI trigger.
The MAXI/GSC nova alert system detected a large X-ray burst from LMXB XTE J1701-407 at 11:43:12 UT on March 29. No significant decay is observed during this scan transit (about 40 sec). The spectrum is well represented by an absorbed blackbody model with a temperature 2.8 +/- 0.3 keV. The hydrogen column density is fixed at 3.3 x 10-22 cm-2 (Degenaar & Wijnands ATel #1572; Markwardt et al. ATel #1569). The unabsorbed bolometric flux is 8.1(+1.1, -1.0) x 10-8 erg/cm2/s. Assuming the flux reaches Eddington limit for a He type-I X-ray burst (3.8 x 1038 erg/s, empirically derived by Kuulkers et al.2003), the distance to the source is 6.2 (+0.5, -0.3) kpc. It is consistent with the result by Falanga et al. 2009 (6.2 kpc), but slightly farther than the result by Chenevez et al. ATel #2814 (5.0 kpc). There is no significant X-ray source at the next scan transit data of MAXI (92 minutes after). NICER observation started at 15:02:03 to 16:40:23 UT with 1.3 ksec exposure. The unabsorbed X-ray flux in the 2 - 10 keV is about 4 x 10-10 erg/cm2/s. Since the flux is consistent with the persistent flux of this source which previously observed by the Swift/XRT (Linares et al. 2009), we conclude that the burst had ended when the NICER observation started (3 hours after the MAXI trigger). We found no significant periodic signal in this data set. The obtained spectrum by NICER is well fitted by an absorbed blackbody model with a temperature 0.8 +/- 0.2 keV plus a powerlaw model with a photon index of 1.9 +/- 0.2. The best-fit hydrogen column density is 3.2 +/- 0.2 x 10-22 cm-2. It is consistent with the value obtained by previous observations (Degenaar & Wijnands ATel #1572; Markwardt et al. ATel #1569). Although we provide only upper limits of the duration of the burst (it is longer than 40 sec), there is a possibility that this event is an new intermediate duration burst (in 't Zand et al. 2005; Cumming et al. 2006) from XTE J1701-407.
