Temperature Structure in the Perseus Cluster Core Observed with Hitomi
Abstract
The present paper investigates the temperature structure of the X-ray emitting plasma in the core of the Perseus cluster using the 1.8--20.0 keV data obtained with the Soft X-ray Spectrometer (SXS) onboard the Hitomi Observatory. A series of four observations were carried out, with a total effective exposure time of 338 ks and covering a central region in diameter. The SXS was operated with an energy resolution of 5 eV (full width at half maximum) at 5.9 keV. Not only fine structures of K-shell lines in He-like ions but also transitions from higher principal quantum numbers are clearly resolved from Si through Fe. This enables us to perform temperature diagnostics using the line ratios of Si, S, Ar, Ca, and Fe, and to provide the first direct measurement of the excitation temperature and ionization temperature in the Perseus cluster. The observed spectrum is roughly reproduced by a single temperature thermal plasma model in collisional ionization equilibrium, but detailed line ratio diagnostics reveal slight deviations from this approximation. In particular, the data exhibit an apparent trend of increasing ionization temperature with increasing atomic mass, as well as small differences between the ionization and excitation temperatures for Fe, the only element for which both temperatures can be measured. The best-fit two-temperature models suggest a combination of 3 and 5 keV gas, which is consistent with the idea that the observed small deviations from a single temperature approximation are due to the effects of projection of the known radial temperature gradient in the cluster core along the line of sight. Comparison with the Chandra/ACIS and the XMM-Newton/RGS results on the other hand suggests that additional lower-temperature components are present in the ICM but not detectable by Hitomi SXS given its 1.8--20 keV energy band.
Cite
@article{arxiv.1712.06612,
title = {Temperature Structure in the Perseus Cluster Core Observed with Hitomi},
author = {Hitomi Collaboration and Felix Aharonian and Hiroki Akamatsu and Fumie Akimoto and Steven W. Allen and Lorella Angelini and Marc Audard and Hisamitsu Awaki and Magnus Axelsson and Aya Bamba and Marshall W. Bautz and Roger Blandford and Laura W. Brenneman and Gregory V. Brown and Esra Bulbul and Edward M. Cackett and Maria Chernyakova and Meng P. Chiao and Paolo S. Coppi and Elisa Costantini and Jelle de Plaa and Cor P. de Vries and Jan-Willem den Herder and Chris Done and Tadayasu Dotani and Ken Ebisawa and Megan E. Eckart and Teruaki Enoto and Yuichiro Ezoe and Andrew C. Fabian and Carlo Ferrigno and Adam R. Foster and Ryuichi Fujimoto and Yasushi Fukazawa and Maki Furukawa and Akihiro Furuzawa and Massimiliano Galeazzi and Luigi C. Gallo and Poshak Gandhi and Margherita Giustini and Andrea Goldwurm and Liyi Gu and Matteo Guainazzi and Yoshito Haba and Kouichi Hagino and Kenji Hamaguchi and Ilana M. Harrus and Isamu Hatsukade and Katsuhiro Hayashi and Takayuki Hayashi and Kiyoshi Hayashida and Junko S. Hiraga and Ann Hornschemeier and Akio Hoshino and John P. Hughes and Yuto Ichinohe and Ryo Iizuka and Hajime Inoue and Yoshiyuki Inoue and Manabu Ishida and Kumi Ishikawa and Yoshitaka Ishisaki and Masachika Iwai and Jelle Kaastra and Tim Kallman and Tsuneyoshi Kamae and Jun Kataoka and Yuichi Kato and Satoru Katsuda and Nobuyuki Kawai and Richard L. Kelley and Caroline A. Kilbourne and Takao Kitaguchi and Shunji Kitamoto and Tetsu Kitayama and Takayoshi Kohmura and Motohide Kokubun and Katsuji Koyama and Shu Koyama and Peter Kretschmar and Hans A. Krimm and Aya Kubota and Hideyo Kunieda and Philippe Laurent and Shiu-Hang Lee and Maurice A. Leutenegger and Olivier Limousin and Michael Loewenstein and Knox S. Long and David Lumb and Greg Madejski and Yoshitomo Maeda and Daniel Maier and Kazuo Makishima and Maxim Markevitch and Hironori Matsumoto and Kyoko Matsushita and Dan McCammon and Brian R. McNamara and Missagh Mehdipour and Eric D. Miller and Jon M. Miller and Shin Mineshige and Kazuhisa Mitsuda and Ikuyuki Mitsuishi and Takuya Miyazawa and Tsunefumi Mizuno and Hideyuki Mori and Koji Mori and Koji Mukai and Hiroshi Murakami and Richard F. Mushotzky and Takao Nakagawa and Hiroshi Nakajima and Takeshi Nakamori and Shinya Nakashima and Kazuhiro Nakazawa and Kumiko K. Nobukawa and Masayoshi Nobukawa and Hirofumi Noda and Hirokazu Odaka and Takaya Ohashi and Masanori Ohno and Takashi Okajima and Naomi Ota and Masanobu Ozaki and Frits Paerels and Stéphane Paltani and Robert Petre and Ciro Pinto and Frederick S. Porter and Katja Pottschmidt and Christopher S. Reynolds and Samar Safi-Harb and Shinya Saito and Kazuhiro Sakai and Toru Sasaki and Goro Sato and Kosuke Sato and Rie Sato and Makoto Sawada and Norbert Schartel and Peter J. Serlemtsos and Hiromi Seta and Megumi Shidatsu and Aurora Simionescu and Randall K. Smith and Yang Soong and Łukasz Stawarz and Yasuharu Sugawara and Satoshi Sugita and Andrew Szymkowiak and Hiroyasu Tajima and Hiromitsu Takahashi and Tadayuki Takahashi and Shiníchiro Takeda and Yoh Takei and Toru Tamagawa and Takayuki Tamura and Takaaki Tanaka and Yasuo Tanaka and Yasuyuki T. Tanaka and Makoto S. Tashiro and Yuzuru Tawara and Yukikatsu Terada and Yuichi Terashima and Francesco Tombesi and Hiroshi Tomida and Yohko Tsuboi and Masahiro Tsujimoto and Hiroshi Tsunemi and Takeshi Go Tsuru and Hiroyuki Uchida and Hideki Uchiyama and Yasunobu Uchiyama and Shutaro Ueda and Yoshihiro Ueda and Shiníchiro Uno and C. Megan Urry and Eugenio Ursino and Shin Watanabe and Norbert Werner and Dan R. Wilkins and Brian J. Williams and Shinya Yamada and Hiroya Yamaguchi and Kazutaka Yamaoka and Noriko Y. Yamasaki and Makoto Yamauchi and Shigeo Yamauchi and Tahir Yaqoob and Yoichi Yatsu and Daisuke Yonetoku and Irina Zhuravleva and Abderahmen Zoghbi},
journal= {arXiv preprint arXiv:1712.06612},
year = {2018}
}
Comments
29 pages, 19 figures, 9 tables. Accepted for publication in PASJ