TY - JOUR
T1 - X-RAY and OPTICAL CORRELATION of TYPE i SEYFERT NGC 3516 STUDIED with SUZAKU and JAPANESE GROUND-BASED TELESCOPES
AU - Noda, Hirofumi
AU - Minezaki, Takeo
AU - Watanabe, Makoto
AU - Kokubo, Mitsuru
AU - Kawaguchi, Kenji
AU - Itoh, Ryosuke
AU - Morihana, Kumiko
AU - Saito, Yoshihiko
AU - Nakao, Hikaru
AU - Imai, Masataka
AU - Moritani, Yuki
AU - Takaki, Katsutoshi
AU - Kawabata, Miho
AU - Nakaoka, Tatsuya
AU - Uemura, Makoto
AU - Kawabata, Koji
AU - Yoshida, Michitoshi
AU - Arai, Akira
AU - Takagi, Yuhei
AU - Morokuma, Tomoki
AU - Doi, Mamoru
AU - Itoh, Yoichi
AU - Yamada, Shin'Ya
AU - Nakazawa, Kazuhiro
AU - Fukazawa, Yasushi
AU - Makishima, Kazuo
N1 - Funding Information:
We thank the referee for his/her valuable comments and suggestions. This work was partly supported by the Grants-in-Aid with grant numbers 26800095 (H.N.), 25287062 (T.M.), and 15J10324 (M.K.) from the Japan Society for the Promotion of Science (JSPS). H.N. was supported by the Special Postdoctoral Researchers Program in RIKEN.
Publisher Copyright:
© 2016. The American Astronomical Society. All rights reserved..
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2016/9/10
Y1 - 2016/9/10
N2 - From 2013 April to 2014 April, we performed X-ray and optical simultaneous monitoring of the type 1.5 Seyfert galaxy NGC 3516. We employed Suzaku and five Japanese ground-based telescopes - the Pirka, Kiso Schmidt, Nayuta, MITSuME, and the Kanata telescopes. The Suzaku observations were conducted seven times with various intervals ranging from days or weeks to months, with an exposure of ∼50 ks each. The optical B-band observations not only covered those of Suzaku almost simultaneously, but also followed the source as frequently as possible. As a result, NGC 3516 was found in its faint phase with a 2-10 keV flux of 0.21-2.70 ×10-11 erg s-1 cm-2. The 2-45 keV X-ray spectra were composed of a dominant variable hard power-law (PL) continuum with a photon index of ∼1.7 and a non-relativistic reflection component with a prominent Fe-Kα emission line. Producing the B-band light curve by differential image photometry, we found that the B-band flux changed by ∼2.7 ×10-11 erg s-1 cm-2, which is comparable to the X-ray variation, and we detected a significant flux correlation between the hard PL component in X-rays and the B-band radiation, for the first time in NGC 3516. By examining their correlation, we found that the X-ray flux preceded that in the B band by 2.0-0.6 +0.07 days (1σ error). Although this result supports the X-ray reprocessing model, the derived lag is too large to be explained by the standard view, which assumes a "lamppost"-type X-ray illuminator located near a standard accretion disk. Our results are better explained by assuming a hot accretion flow and a truncated disk.
AB - From 2013 April to 2014 April, we performed X-ray and optical simultaneous monitoring of the type 1.5 Seyfert galaxy NGC 3516. We employed Suzaku and five Japanese ground-based telescopes - the Pirka, Kiso Schmidt, Nayuta, MITSuME, and the Kanata telescopes. The Suzaku observations were conducted seven times with various intervals ranging from days or weeks to months, with an exposure of ∼50 ks each. The optical B-band observations not only covered those of Suzaku almost simultaneously, but also followed the source as frequently as possible. As a result, NGC 3516 was found in its faint phase with a 2-10 keV flux of 0.21-2.70 ×10-11 erg s-1 cm-2. The 2-45 keV X-ray spectra were composed of a dominant variable hard power-law (PL) continuum with a photon index of ∼1.7 and a non-relativistic reflection component with a prominent Fe-Kα emission line. Producing the B-band light curve by differential image photometry, we found that the B-band flux changed by ∼2.7 ×10-11 erg s-1 cm-2, which is comparable to the X-ray variation, and we detected a significant flux correlation between the hard PL component in X-rays and the B-band radiation, for the first time in NGC 3516. By examining their correlation, we found that the X-ray flux preceded that in the B band by 2.0-0.6 +0.07 days (1σ error). Although this result supports the X-ray reprocessing model, the derived lag is too large to be explained by the standard view, which assumes a "lamppost"-type X-ray illuminator located near a standard accretion disk. Our results are better explained by assuming a hot accretion flow and a truncated disk.
KW - X-rays: galaxies
KW - galaxies: Seyfert
KW - galaxies: active
KW - galaxies: individual (NGC 3516)
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U2 - 10.3847/0004-637X/828/2/78
DO - 10.3847/0004-637X/828/2/78
M3 - Article
AN - SCOPUS:84991693280
VL - 828
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 78
ER -