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arXiv · 1711.07727

Glimpse of the highly obscured HMXB IGR J16318-4848 with Hitomi

Hitomi Collaboration·Felix Aharonian·Hiroki Akamatsu·Fumie Akimoto·Steven W. Allen·Lorella Angelini·Marc Audard·Hisamitsu Awaki·Magnus Axelsson·Aya Bamba·Marshall W. Bautz·Roger Blandford·Laura W. Brenneman·Gregory V. Brown·Esra Bulbul·Edward M. Cackett·Maria Chernyakova·Meng P. Chiao·Paolo S. Coppi·Elisa Costantini·Jelle de Plaa·Cor P. de Vries·Jan-Willem den Herder·Chris Done·Tadayasu Dotani·Ken Ebisawa·Megan E. Eckart·Teruaki Enoto·Yuichiro Ezoe·Andrew C. Fabian·Carlo Ferrigno·Adam R. Foster·Ryuichi Fujimoto·Yasushi Fukazawa·Akihiro Furuzawa·Massimiliano Galeazzi·Luigi C. Gallo·Poshak Gandhi·Margherita Giustini·Andrea Goldwurm·Liyi Gu·Matteo Guainazzi·Yoshito Haba·Kouichi Hagino·Kenji Hamaguchi·Ilana M. Harrus·Isamu Hatsukade·Katsuhiro Hayashi·Takayuki Hayashi·Kiyoshi Hayashida·Junko S. Hiraga·Ann Hornschemeier·Akio Hoshino·John P. Hughes·Yuto Ichinohe·Ryo Iizuka·Hajime Inoue·Yoshiyuki Inoue·Manabu Ishida·Kumi Ishikawa·Yoshitaka Ishisaki·Masachika Iwai·Jelle Kaastra·Tim Kallman·Tsuneyoshi Kamae·Jun Kataoka·Satoru Katsuda·Nobuyuki Kawai·Richard L. Kelley·Caroline A. Kilbourne·Takao Kitaguchi·Shunji Kitamoto·Tetsu Kitayama·Takayoshi Kohmura·Motohide Kokubun·Katsuji Koyama·Shu Koyama·Peter Kretschmar·Hans A. Krimm·Aya Kubota·Hideyo Kunieda·Philippe Laurent·Shiu-Hang Lee·Maurice A. Leutenegger·Olivier O. Limousin·Michael Loewenstein·Knox S. Long·David Lumb·Greg Madejski·Yoshitomo Maeda·Daniel Maier·Kazuo Makishima·Maxim Markevitch·Hironori Matsumoto·Kyoko Matsushita·Dan McCammon·Brian R. McNamara·Missagh Mehdipour·Eric D. Miller·Jon M. Miller
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Abstract

We report a Hitomi observation of IGR J16318-4848, a high-mass X-ray binary system with an extremely strong absorption of N_H~10^{24} cm^{-2}. Previous X-ray studies revealed that its spectrum is dominated by strong fluorescence lines of Fe as well as continuum emission. For physical and geometrical insight into the nature of the reprocessing material, we utilize the high spectroscopic resolving power of the X-ray microcalorimeter (the soft X-ray spectrometer; SXS) and the wide-band sensitivity by the soft and hard X-ray imager (SXI and HXI) aboard Hitomi. Even though photon counts are limited due to unintended off-axis pointing, the SXS spectrum resolves Fe K{α_1} and K{α_2} lines and puts strong constraints on the line centroid and width. The line width corresponds to the velocity of 160^{+300}_{-70} km s^{-1}. This represents the most accurate, and smallest, width measurement of this line made so far from any X-ray binary, much less than the Doppler broadening and shift expected from speeds which are characteristic of similar systems. Combined with the K-shell edge energy measured by the SXI and HXI spectra, the ionization state of Fe is estimated to be in the range of Fe I--IV. Considering the estimated ionization parameter and the distance between the X-ray source and the absorber, the density and thickness of the materials are estimated. The extraordinarily strong absorption and the absence of a Compton shoulder component is confirmed. These characteristics suggest reprocessing materials which are distributed in a narrow solid angle or scattering primarily with warm free electrons or neutral hydrogen.

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Hitomi Collaboration, Felix Aharonian, Hiroki Akamatsu, Fumie Akimoto, Steven W. Allen, Lorella Angelini, Marc Audard, Hisamitsu Awaki, Magnus Axelsson, Aya Bamba, Marshall W. Bautz, Roger Blandford, Laura W. Brenneman, Gregory V. Brown, Esra Bulbul, Edward M. Cackett, Maria Chernyakova, Meng P. Chiao, Paolo S. Coppi, Elisa Costantini, Jelle de Plaa, Cor P. de Vries, Jan-Willem den Herder, Chris Done, Tadayasu Dotani, Ken Ebisawa, Megan E. Eckart, Teruaki Enoto, Yuichiro Ezoe, Andrew C. Fabian, Carlo Ferrigno, Adam R. Foster, Ryuichi Fujimoto, Yasushi Fukazawa, Akihiro Furuzawa, Massimiliano Galeazzi, Luigi C. Gallo, Poshak Gandhi, Margherita Giustini, Andrea Goldwurm, Liyi Gu, Matteo Guainazzi, Yoshito Haba, Kouichi Hagino, Kenji Hamaguchi, Ilana M. Harrus, Isamu Hatsukade, Katsuhiro Hayashi, Takayuki Hayashi, Kiyoshi Hayashida, Junko S. Hiraga, Ann Hornschemeier, Akio Hoshino, John P. Hughes, Yuto Ichinohe, Ryo Iizuka, Hajime Inoue, Yoshiyuki Inoue, Manabu Ishida, Kumi Ishikawa, Yoshitaka Ishisaki, Masachika Iwai, Jelle Kaastra, Tim Kallman, Tsuneyoshi Kamae, Jun Kataoka, Satoru Katsuda, Nobuyuki Kawai, Richard L. Kelley, Caroline A. Kilbourne, Takao Kitaguchi, Shunji Kitamoto, Tetsu Kitayama, Takayoshi Kohmura, Motohide Kokubun, Katsuji Koyama, Shu Koyama, Peter Kretschmar, Hans A. Krimm, Aya Kubota, Hideyo Kunieda, Philippe Laurent, Shiu-Hang Lee, Maurice A. Leutenegger, Olivier O. Limousin, Michael Loewenstein, Knox S. Long, David Lumb, Greg Madejski, Yoshitomo Maeda, Daniel Maier, Kazuo Makishima, Maxim Markevitch, Hironori Matsumoto, Kyoko Matsushita, Dan McCammon, Brian R. McNamara, Missagh Mehdipour, Eric D. Miller, Jon M. Miller. 2017-11-21. Glimpse of the highly obscured HMXB IGR J16318-4848 with Hitomi. https://doi.org/10.1093/pasj%2Fpsx154

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