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MAXI/GSC observations of IceCube-170922A and TXS 0506+056

ATel #10838; H. Negoro (Nihon U.), S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai (JAXA), T. Mihara, M. Sugizaki, S. Nakahira, W. Iwakiri, M. Shidatsu, F. Yatabe, Y. Takao, M. Matsuoka (RIKEN), N. Kawai, S. Sugita, T. Yoshii, Y. Tachibana, S. Harita, K. Morita (Tokyo Tech), A. Yoshida, T. Sakamoto, M. Serino, Y. Kawakubo, Y. Kitaoka, T. Hashimoto (AGU), H. Tsunemi, T. Yoneyama (Osaka U.), M. Nakajima, T. Kawase, A. Sakamaki (Nihon U.), Y. Ueda, T. Hori, A. Tanimoto, S. Oda
on 11 Oct 2017; 02:36 UT
Credential Certification: Hitoshi Negoro (negoro@phys.cst.nihon-u.ac.jp)

Subjects: X-ray, Blazar

Referred to by ATel #: 10840, 10844, 10861

We reexamine MAXI/GSC data for the high-energy neutrino event IceCube-170922A detected at 20:54:30.43 on 2017 September 22 (GCN #21916), and recently active blazer TXS 0506+056 in the IceCube error region (ATel #10791, #10792, #10794, #10799, #10801, #10817, #10830, #10831, #10833, also see ATel #10773, 17787).

MAXI/GSC scanned the IceCube error region at 20:49 and 22:21 on September 22 before and after the event, and detected no significant X-ray enhancement. The 4-10 keV 1-sigma upper limits are both 16 mCrab.

We also produced 2-4 keV and 4-10 keV X-ray light curves at the position of TXS 0506+056 with the PSF-fit method (Morii et al. 2016, PASJ, 68, S11). The 4-10 keV X-ray light curve shows a flare-like event peaking at 0.040 (+0.022, -0.019) c/s/cm2 (~34 mCrab) in the scan transit at 16:53 on September 23, and the 4-10 keV X-ray flux averaged over 4 scans from 12:15 to 16:53 on September 23 is 0.021(+0.009, -0.008) c/s/cm2 (~ 18 mCrab, 2.6 sigma level detection). The 2-4 keV X-ray light curve, however, do not show similar excess for the above period. and the point-source is not so visible even in the 4-10 keV X-ray image.

Any flux excess corresponding to the Gamma-ray flare after September 15 (ATel #10791) is not recognized either in the 2-4 keV or 4-10 keV X-ray longterm light curve.