XRISM Forecast for the Coma Cluster: Stormy, with a Steep Power Spectrum


Journal article


M. Audard, H. Awaki, R. Ballhausen, A. Bamba, E. Behar, R. Boissay-Malaquin, L. Brenneman, Gregory V. Brown, Lia Corrales, E. Costantini, R. Cumbee, M. Díaz Trigo, C. Done, T. Dotani, K. Ebisawa, M. Eckart, D. Eckert, Satoshi Eguchi, T. Enoto, Y. Ezoe, Adam R. Foster, R. Fujimoto, Y. Fujita, Y. Fukazawa, Kotaro Fukushima, A. Furuzawa, L. Gallo, Javier A. García, Liyi Gu, M. Guainazzi, Kouichi Hagino, Kenji Hamaguchi, I. Hatsukade, K. Hayashi, T. Hayashi, N. Hell, E. Hodges-Kluck, A. Hornschemeier, Y. Ichinohe, D. Ishi, Manabu Ishida, K. Ishikawa, Y. Ishisaki, J. Kaastra, T. Kallman, Erin Kara, S. Katsuda, Y. Kanemaru, Rich Kelley, C. Kilbourne, S. Kitamoto, S. Kobayashi, T. Kohmura, A. Kubota, M. Leutenegger, M. Loewenstein, Y. Maeda, M. Markevitch, Hironori Matsumoto, K. Matsushita, D. McCammon, Brian McNamara, F. Mernier, E. Miller, Jon M. Miller, I. Mitsuishi, M. Mizumoto, T. Mizuno, K. Mori, K. Mukai, Hiroshi Murakami, R. Mushotzky, H. Nakajima, K. Nakazawa, J. Ness, K. Nobukawa, M. Nobukawa, Hirofumi Noda, H. Odaka, S. Ogawa, A. Ogorzałek, T. Okajima, Naomi Ota, S. Paltani, R. Petre, P. Plucinsky, F. Porter, K. Pottschmidt, Kosuke Sato, Toshiki Sato, M. Sawada, H. Seta, M. Shidatsu, A. Simionescu, Randall Smith, Hiromasa Suzuki, A. Szymkowiak, H. Takahashi, M. Takeo, T. Tamagawa, Keisuke Tamura, Takaaki Tanaka, A. Tanimoto, M. Tashiro, Y. Terada, Y. Terashima, Y. Tsuboi, M. Tsujimoto, H. Tsunemi, T. Tsuru, Ayşegül Tümer, Hiroyuki Uchida, N. Uchida, Y. Uchida, H. Uchiyama, S. Ueda, Y. Ueda, S. Uno, J. Vink, S. Watanabe, Brian J. Williams, S. Yamada, S. Yamada, Hiroya Yamaguchi, K. Yamaoka, N. Yamasaki, M. Yamauchi, S. Yamauchi, T. Yaqoob, T. Yoneyama, Tessei Yoshida, M. Yukita, I. Zhuravleva, A. Fabian, D. Nelson, N. Okabe, A. Pillepich, Cicely Potter, M. Regamey, Kosei Sakai, Mona Shishido, N. Truong, D. Wik, J. Zuhone
Astrophysical Journal Letters, 2025

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APA   Click to copy
Audard, M., Awaki, H., Ballhausen, R., Bamba, A., Behar, E., Boissay-Malaquin, R., … Zuhone, J. (2025). XRISM Forecast for the Coma Cluster: Stormy, with a Steep Power Spectrum. Astrophysical Journal Letters.


Chicago/Turabian   Click to copy
Audard, M., H. Awaki, R. Ballhausen, A. Bamba, E. Behar, R. Boissay-Malaquin, L. Brenneman, et al. “XRISM Forecast for the Coma Cluster: Stormy, with a Steep Power Spectrum.” Astrophysical Journal Letters (2025).


MLA   Click to copy
Audard, M., et al. “XRISM Forecast for the Coma Cluster: Stormy, with a Steep Power Spectrum.” Astrophysical Journal Letters, 2025.


BibTeX   Click to copy

@article{m2025a,
  title = {XRISM Forecast for the Coma Cluster: Stormy, with a Steep Power Spectrum},
  year = {2025},
  journal = {Astrophysical Journal Letters},
  author = {Audard, M. and Awaki, H. and Ballhausen, R. and Bamba, A. and Behar, E. and Boissay-Malaquin, R. and Brenneman, L. and Brown, Gregory V. and Corrales, Lia and Costantini, E. and Cumbee, R. and Trigo, M. Díaz and Done, C. and Dotani, T. and Ebisawa, K. and Eckart, M. and Eckert, D. and Eguchi, Satoshi and Enoto, T. and Ezoe, Y. and Foster, Adam R. and Fujimoto, R. and Fujita, Y. and Fukazawa, Y. and Fukushima, Kotaro and Furuzawa, A. and Gallo, L. and García, Javier A. and Gu, Liyi and Guainazzi, M. and Hagino, Kouichi and Hamaguchi, Kenji and Hatsukade, I. and Hayashi, K. and Hayashi, T. and Hell, N. and Hodges-Kluck, E. and Hornschemeier, A. and Ichinohe, Y. and Ishi, D. and Ishida, Manabu and Ishikawa, K. and Ishisaki, Y. and Kaastra, J. and Kallman, T. and Kara, Erin and Katsuda, S. and Kanemaru, Y. and Kelley, Rich and Kilbourne, C. and Kitamoto, S. and Kobayashi, S. and Kohmura, T. and Kubota, A. and Leutenegger, M. and Loewenstein, M. and Maeda, Y. and Markevitch, M. and Matsumoto, Hironori and Matsushita, K. and McCammon, D. and McNamara, Brian and Mernier, F. and Miller, E. and Miller, Jon M. and Mitsuishi, I. and Mizumoto, M. and Mizuno, T. and Mori, K. and Mukai, K. and Murakami, Hiroshi and Mushotzky, R. and Nakajima, H. and Nakazawa, K. and Ness, J. and Nobukawa, K. and Nobukawa, M. and Noda, Hirofumi and Odaka, H. and Ogawa, S. and Ogorzałek, A. and Okajima, T. and Ota, Naomi and Paltani, S. and Petre, R. and Plucinsky, P. and Porter, F. and Pottschmidt, K. and Sato, Kosuke and Sato, Toshiki and Sawada, M. and Seta, H. and Shidatsu, M. and Simionescu, A. and Smith, Randall and Suzuki, Hiromasa and Szymkowiak, A. and Takahashi, H. and Takeo, M. and Tamagawa, T. and Tamura, Keisuke and Tanaka, Takaaki and Tanimoto, A. and Tashiro, M. and Terada, Y. and Terashima, Y. and Tsuboi, Y. and Tsujimoto, M. and Tsunemi, H. and Tsuru, T. and Tümer, Ayşegül and Uchida, Hiroyuki and Uchida, N. and Uchida, Y. and Uchiyama, H. and Ueda, S. and Ueda, Y. and Uno, S. and Vink, J. and Watanabe, S. and Williams, Brian J. and Yamada, S. and Yamada, S. and Yamaguchi, Hiroya and Yamaoka, K. and Yamasaki, N. and Yamauchi, M. and Yamauchi, S. and Yaqoob, T. and Yoneyama, T. and Yoshida, Tessei and Yukita, M. and Zhuravleva, I. and Fabian, A. and Nelson, D. and Okabe, N. and Pillepich, A. and Potter, Cicely and Regamey, M. and Sakai, Kosei and Shishido, Mona and Truong, N. and Wik, D. and Zuhone, J.}
}

Abstract

The XRISM Resolve microcalorimeter array measured the velocities of hot intracluster gas at two positions in the Coma galaxy cluster: 3′×3′ squares at the center and at 6 ′ (170 kpc) to the south. We find the line-of-sight velocity dispersions in those regions to be σz = 208 ± 12 km s−1 and 202 ± 24 km s−1, respectively. The central value corresponds to a 3D Mach number of M = 0.24 ± 0.015 and a ratio of the kinetic pressure of small-scale motions to thermal pressure in the intracluster plasma of only 3.1% ± 0.4%, at the lower end of predictions from cosmological simulations for merging clusters like Coma, and similar to that observed in the cool core of the relaxed cluster A2029. Meanwhile, the gas in both regions exhibits high line-of-sight velocity differences from the mean velocity of the cluster galaxies, Δvz = 450 ± 15 km s−1 and 730 ± 30 km s−1, respectively. A small contribution from an additional gas velocity component, consistent with the cluster optical mean, is detected along a sight line near the cluster center. The combination of the observed velocity dispersions and bulk velocities is not described by a Kolmogorov velocity power spectrum of steady-state turbulence; instead, the data imply a much steeper effective slope (i.e., relatively more power at larger linear scales). This may indicate either a very large dissipation scale, resulting in the suppression of small-scale motions, or a transient dynamic state of the cluster, where large-scale gas flows generated by an ongoing merger have not yet cascaded down to small scales.