Hitomi Observation of Radio Galaxy NGC 1275: The First X-ray Microcalorimeter Spectroscopy of Fe-Kα Line Emission from an Active Galactic Nucleus
Creators: name: Hitomi Collaboration
name: Aharonian, Felix
name: Akamatsu, Hiroki
name: Akimoto, Fumie
name: Allen, Steven W.
name: Angelini, Lorella
name: Audard, Marc
name: Awaki, Hisamitsu
name: Axelsson, Magnus
name: Bamba, Aya
name: Bautz, Marshall W.
name: Blandford, Roger
name: Brenneman, Laura W.
name: Brown, Gregory V.
name: Bulbul, Esra
name: Cackett, Edward M.
name: Chernyakova, Maria
name: Chiao, Meng P.
name: Coppi, Paolo S.
name: Costantini, Elisa
name: de Plaa, Jelle
name: de Vries, Cor P.
name: Herder, Jan-Willem den
name: Done, Chris
name: Dotani, Tadayasu
name: Ebisawa, Ken
name: Eckart, Megan E.
name: Enoto, Teruaki
name: Ezoe, Yuichiro
name: Fabian, Andrew C.
name: Ferrigno, Carlo
name: Foster, Adam R.
name: Fujimoto, Ryuichi
name: Fukazawa, Yasushi
name: Furuzawa, Akihiro
name: Galeazzi, Massimiliano
name: Gallo, Luigi C.
name: Gandhi, Poshak
name: Giustini, Margherita
name: Goldwurm, Andrea
name: Gu, Liyi
name: Guainazzi, Matteo
name: Haba, Yoshito
name: Hagino, Kouichi
name: Hamaguchi, Kenji
name: Harrus, Ilana M.
name: Hatsukade, Isamu
name: Hayashi, Katsuhiro
name: Hayashi, Takayuki
name: Hayashida, Kiyoshi
name: Hiraga, Junko S.
name: Hornschemeier, Ann
name: Hoshino, Akio
name: Hughes, John P.
name: Ichinohe, Yuto
name: Iizuka, Ryo
name: Inoue, Hajime
name: Inoue, Yoshiyuki
name: Ishida, Manabu
name: Ishikawa, Kumi
name: Ishisaki, Yoshitaka
name: Iwai, Masachika
name: Kaastra, Jelle
name: Kallman, Tim
name: Kamae, Tsuneyoshi
name: Kataoka, Jun
name: Katsuda, Satoru
name: Kawai, Nobuyuki
name: Kelley, Richard L.
name: Kilbourne, Caroline A.
name: Kitaguchi, Takao
name: Kitamoto, Shunji
name: Kitayama, Tetsu
name: Kohmura, Takayoshi
name: Kokubun, Motohide
name: Koyama, Katsuji
name: Koyama, Shu
name: Kretschmar, Peter
name: Krimm, Hans A.
name: Kubota, Aya
name: Kunieda, Hideyo
name: Laurent, Philippe
name: Lee, Shiu-Hang
name: Leutenegger, Maurice A.
name: Limousin, Olivier O.
name: Loewenstein, Michael
name: Long, Knox S.
name: Lumb, David
name: Madejski, Greg
name: Maeda, Yoshitomo
name: Maier, Daniel
name: Makishima, Kazuo
name: Markevitch, Maxim
name: Matsumoto, Hironori
name: Matsushita, Kyoko
name: McCammon, Dan
name: McNamara, Brian R.
name: Mehdipour, Missagh
name: Miller, Eric D.
name: Miller, Jon M.
name: Mineshige, Shin
name: Mitsuda, Kazuhisa
name: Mitsuishi, Ikuyuki
name: Miyazawa, Takuya
name: Mizuno, Tsunefumi
name: Mori, Hideyuki
name: Mori, Koji
name: Mukai, Koji
name: Murakami, Hiroshi
name: Mushotzky, Richard F.
name: Nakagawa, Takao
name: Nakajima, Hiroshi
name: Nakamori, Takeshi
name: Nakashima, Shinya
name: Nakazawa, Kazuhiro
name: Nobukawa, Kumiko K.
name: Nobukawa, Masayoshi
name: Noda, Hirofumi
name: Odaka, Hirokazu
name: Ohashi, Takaya
name: Ohno, Masanori
name: Okajima, Takashi
name: Ota, Naomi
name: Ozaki, Masanobu
name: Paerels, Frits
name: Paltani, Stéphane
name: Petre, Robert
name: Pinto, Ciro
name: Porter, Frederick S.
name: Pottschmidt, Katja
name: Reynolds, Christopher S.
name: Safi-Harb, Samar
name: Saito, Shinya
name: Sakai, Kazuhiro
name: Sasaki, Toru
name: Sato, Goro
name: Sato, Kosuke
name: Sato, Rie
name: Sawada, Makoto
name: Schartel, Norbert
name: Serlemitsos, Peter J.
name: Seta, Hiromi
name: Shidatsu, Megumi
name: Simionescu, Aurora
name: Smith, Randall K.
name: Soong, Yang
name: Stawarz, Łukasz
name: Sugawara, Yasuharu
name: Sugita, Satoshi
name: Szymkowiak, Andrew
name: Tajima, Hiroyasu
name: Takahashi, Hiromitsu
name: Takahashi, Tadayuki
name: Takeda, Shin'ichiro
name: Takei, Yoh
name: Tamagawa, Toru
name: Tamura, Takayuki
name: Tanaka, Takaaki
name: Tanaka, Yasuo
name: Tanaka, Yasuyuki T.
name: Tashiro, Makoto S.
name: Tawara, Yuzuru
name: Terada, Yukikatsu
name: Terashima, Yuichi
name: Tombesi, Francesco
name: Tomida, Hiroshi
name: Tsuboi, Yohko
name: Tsujimoto, Masahiro
name: Tsunemi, Hiroshi
name: Tsuru, Takeshi Go
name: Uchida, Hiroyuki
name: Uchiyama, Hideki
name: Uchiyama, Yasunobu
name: Ueda, Shutaro
name: Ueda, Yoshihiro
name: Uno, Shin'ichiro
name: Urry, C. Megan
name: Ursino, Eugenio
name: Watanabe, Shin
name: Werner, Norbert
name: Wilkins, Dan R.
name: Williams, Brian J.
name: Yamada, Shinya
name: Yamaguchi, Hiroya
name: Yamaoka, Kazutaka
name: Yamasaki, Noriko Y.
name: Yamauchi, Makoto
name: Yamauchi, Shigeo
name: Yaqoob, Tahir
name: Yatsu, Yoichi
name: Yonetoku, Daisuke
name: Zhuravleva, Irina
name: Zoghbi, Abderahmen
name: Kawamuro, Taiki
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: The origin of the narrow Fe-Kα fluorescence line at 6.4 keV from active galactic nuclei has long been under debate; some of the possible sites are the outer accretion disk, the broad line region, a molecular torus, or interstellar/intracluster media. In February-March 2016, we performed the first X-ray microcalorimeter spectroscopy with the Soft X-ray Spectrometer (SXS) onboard the Hitomi satellite of the Fanaroff-Riley type I radio galaxy NGC 1275 at the center of the Perseus cluster of galaxies. With the high energy resolution of ~5 eV at 6 keV achieved by Hitomi/SXS, we detected the Fe-Kα line with ~5.4 σ significance. The velocity width is constrained to be 500-1600 km s$^{-1}$ (FWHM for Gaussian models) at 90% confidence. The SXS also constrains the continuum level from the NGC 1275 nucleus up to ~20 keV, giving an equivalent width ~20 eV of the 6.4 keV line. Because the velocity width is narrower than that of broad Hα line of ~2750 km s$^{-1}$, we can exclude a large contribution to the line flux from the accretion disk and the broad line region. Furthermore, we performed pixel map analyses on the Hitomi/SXS data and image analyses on the Chandra archival data, and revealed that the Fe-Kα line comes from a region within ~1.6 kpc from the NGC 1275 core, where an active galactic nucleus emission dominates, rather than that from intracluster media. Therefore, we suggest that the source of the Fe-Kα line from NGC 1275 is likely a low-covering fraction molecular torus or a rotating molecular disk which probably extends from a pc to hundreds pc scale in the active galactic nucleus system.
description: 20 pages, 8 figures, 6 tables, accepted for publication in PASJ