OISTER optical and near-infrared monitoring observations of peculiar radio-loud active galactic nucleus SDSS J110006.07+442144.3

Tomoki Morokuma,Masaomi Tanaka,Yasuyuki T. Tanaka,Ryosuke Itoh,Nozomu Tominaga,Poshak Gandhi,Elena Pian,Paolo Mazzali,Kouji Ohta,Emiko Matsumoto,Takumi Shibata,Hinako Akimoto,Hiroshi Akitaya,Gamal B. Ali,Tsutomu Aoki,Mamoru Doi,Nana Ebisuda,Ahmed Essam,Kenta Fujisawa,Hideo Fukushima,Shuhei Goda,Yuya Gouda,Hidekazu Hanayama,Yasuhito Hashiba,Osamu Hashimoto,Kenzo Hayashida,Yuichiro Hiratsuka,Satoshi Honda,Masataka Imai,Kanichiro Inoue,Michiko Ishibashi,Ikuru Iwata,Hideyuki Izumiura,Yuka Kanda,Miho Kawabata,Kenji Kawaguchi,Nobuyuki Kawai,Mitsuru Kokubo,Daisuke Kuroda,Hiroyuki Maehara,Hiroyuki Mito,Kazuma Mitsuda,Ryota Miyagawa,Takeshi Miyaji,Yusuke Miyamoto,Kumiko Morihana,Yuki Moritani,Kana Morokuma-Matsui,Kotone Murakami,Katsuhiro L. Murata,Takahiro Nagayama,Kazuki Nakamura,Tatsuya Nakaoka,Kotaro Niinuma,Takafumi Nishimori,Daisaku Nogami,Yumiko Oasa,Tatsunori Oda,Tomohito Ohshima,Yoshihiko Saito,Shuichiro Sakata,Shigeyuki Sako,Yuki Sarugaku,Satoko Sawada-Satoh,Genta Seino, et al.

We present monitoring campaign observations at optical and near-infrared (NIR) wavelengths for a radio-loud active galactic nucleus (AGN) at z = 0.840, SDSS J110006.07+442144.3 (hereafter, J1100+4421), which was identified during a flare phase in late 2014 February. The campaigns consist of three intensive observing runs from the discovery to 2015 March, mostly within the scheme of the OISTER collaboration. Optical-NIR light curves and simultaneous spectral energy distributions (SEDs) are obtained. Our measurements show the strongest brightening in 2015 March. We found that the optical-NIR SEDs of J1100+4421 show an almost steady shape despite the large and rapid intranight variability. This constant SED shape is confirmed to extend to ∼5 μm in the observed frame using the archival WISE data. Given the lack of absorption lines and the steep power-law spectrum of αν ∼ -1.4, where f_{ν }∝ ν ^{α _{ν }}, synchrotron radiation by a relativistic jet with no or small contributions from the host galaxy and the accretion disk seems most plausible as an optical-NIR emission mechanism. The steep optical-NIR spectral shape and the large amplitude of variability are consistent with this object being a low νpeak jet-dominated AGN. In addition, sub-arcsecond resolution optical imaging data taken with Subaru Hyper Suprime-Cam does not show a clear extended component and the spatial scales are significantly smaller than the large extensions detected at radio wavelengths. The optical spectrum of a possible faint companion galaxy does not show any emission lines at the same redshift, and hence a merging hypothesis for this AGN-related activity is not supported by our observations.

Publications of the Astronomical Society of Japan

Oxford University Press (OUP)

69

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10.1093/pasj/psx075