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arXiv · 1304.2453

Dense optical and near-infrared monitoring of CTA 102 during high state in 2012 with OISTER: Detection of intra-night "orphan polarized flux flare"

Ryosuke Itoh·Yasushi Fukazawa·Yasuyuki T. Tanaka·Yuhei Abe·Hiroshi Akitaya·Akira Arai·Masahiko Hayashi·Takafumi Hori·Mizuki Isogai·Hideyuki Izumiura·Koji S. Kawabata·Nobuyuki Kawai·Daisuke Kuroda·Ryo Miyanoshita·Yuki Moritani·Tomoki Morokuma·Takahiro Nagayama·Jumpei Nakamoto·Chikako Nakata·Yumiko Oasa·Tomohito Ohshima·Takashi Ohsugi·Shin-ichiro Okumura·Yoshihiko Saito·Yu Saito·Mahito Sasada·Kazuhiro Sekiguchi·Yuhei Takagi·Jun Takahashi·Yukihiro Takahashi·Katsutoshi Takaki·Makoto Uemura·Issei Ueno·Seitaro Urakawa·Makoto Watanabe·Masayuki Yamanaka·Yoshinori Yonekura·Michitoshi Yoshida
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Abstract

CTA 102, classified as a flat spectrum radio quasar at z=1.037, produced exceptionally bright optical flare in 2012 September. Following Fermi-LAT detection of enhanced gamma-ray activity, we densely monitored this source in the optical and near-infrared bands for the subsequent ten nights using twelve telescopes in Japan and South-Africa. On MJD 56197 (2012 September 27, 4-5 days after the peak of bright gamma-ray flare), polarized flux showed a transient increase, while total flux and polarization angle remained almost constant during the "orphan polarized-flux flare". We also detected an intra-night and prominent flare on MJD 56202. The total and polarized fluxes showed quite similar temporal variations, but PA again remained constant during the flare. Interestingly, the polarization angles during the two flares were significantly different from the jet direction. Emergence of a new emission component with high polarization degree (PD) up to 40% would be responsible for the observed two flares, and such a high PD indicates a presence of highly ordered magnetic field at the emission site. We discuss that the well-ordered magnetic field and even the observed directions of polarization angle which is grossly perpendicular to the jet are reasonably accounted for by transverse shock(s) propagating down the jet.

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Ryosuke Itoh, Yasushi Fukazawa, Yasuyuki T. Tanaka, Yuhei Abe, Hiroshi Akitaya, Akira Arai, Masahiko Hayashi, Takafumi Hori, Mizuki Isogai, Hideyuki Izumiura, Koji S. Kawabata, Nobuyuki Kawai, Daisuke Kuroda, Ryo Miyanoshita, Yuki Moritani, Tomoki Morokuma, Takahiro Nagayama, Jumpei Nakamoto, Chikako Nakata, Yumiko Oasa, Tomohito Ohshima, Takashi Ohsugi, Shin-ichiro Okumura, Yoshihiko Saito, Yu Saito, Mahito Sasada, Kazuhiro Sekiguchi, Yuhei Takagi, Jun Takahashi, Yukihiro Takahashi, Katsutoshi Takaki, Makoto Uemura, Issei Ueno, Seitaro Urakawa, Makoto Watanabe, Masayuki Yamanaka, Yoshinori Yonekura, Michitoshi Yoshida. 2013-04-09. Dense optical and near-infrared monitoring of CTA 102 during high state in 2012 with OISTER: Detection of intra-night "orphan polarized flux flare". https://doi.org/10.1088/2041-8205%2F768%2F2%2Fl24

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