Follow-up observations for IceCube-170922A: Detection of rapid near-infrared variability and intensive monitoring of TXS 0506+056. (22nd January 2021)

• Record Type: Journal Article
• Authors: Morokuma, Tomoki; Utsumi, Yousuke; Ohta, Kouji; Yamanaka, Masayuki; Kawabata, Koji S; Inoue, Yoshiyuki; Tanaka, Masaomi; Yoshida, Michitoshi; Itoh, Ryosuke; Sasada, Mahito; Tominaga, Nozomu; Mori, Hiroki; Kawabata, Miho; Nakaoka, Tatsuya; Chogi, Maiko; Abe, Taisei; Huang, Ruochen; Kawahara, Naoki; Kimura, Hiroki; Nagashima, Hiroki; Takagi, Kengo; Yamazaki, Yuina; Liu, Wei; Ohsawa, Ryou; Sako, Shigeyuki; Murata, Katsuhiro L; Morihana, Kumiko; Gilligan, Christina K; Isogai, Keisuke; Kimura, Mariko; Wakamatsu, Yasuyuki; Ohnishi, Ryuhei; Takayama, Masaki; Honda, Satoshi; Matsuoka, Yoshiki; Yamashita, Takuji; Nagataki, Shigehiro; Tanaka, Yasuyuki T;
• Is Part Of: Publications of the Astronomical Society of Japan. Volume 73:Number 1(2021)
• Page Start: 25
• Page End: 43
• Publication Date: 2021-01-22
• Subjects: BL Lacertae objects: general -- BL Lacertae objects: individual (TXS 0506+056) -- galaxies: active -- neutrinos -- relativistic processes -- surveys; Astronomy -- Periodicals; 520.5
• DOI: 10.1093/pasj/psaa110
• Languages: English
• ISSNs: 0004-6264

Abstract

Abstract: We present our follow-up observations to search for an electromagnetic counterpart of the IceCube high-energy neutrino IceCube-170922A. Monitoring observations of a likely counterpart, TXS 0506+056, are also described. First, we quickly took optical and near-infrared images of seven flat-spectrum radio sources within the IceCube error region right after the neutrino detection and found a rapid flux decline of TXS 0506+056 in Kanata/HONIR J -band data. Motivated by this discovery, intensive follow-up observations of TXS 0506+056 were continuously performed, including our monitoring imaging observations, spectroscopic observations, and polarimetric observations in optical and near-infrared wavelengths. TXS 0506+056 showed a large-amplitude (∼1.0 mag) variability in a time scale of several days or longer, although no significant variability was detected in a time scale of a day or shorter. TXS 0506+056 also showed a bluer-when-brighter trend in optical and near-infrared wavelengths. Structure functions of the variabilities were examined and indicate that TXS 0506+056 is not a special blazar in terms of optical variability. Polarization measurement results of TXS 0506+056 are also discussed.