Understanding why galaxy clusters are warm may explain the origin of giant interstellar structures
- Date:
- May 2, 2025
- Source:
- Nagoya University
- Summary:
- Astronomers have explained how a galaxy cluster maintains its heat, despite emitting X-rays that cool the hot gas at its center. The group discovered the existence of a fast-moving, high-temperature gas flow in the center of the Centaurus cluster. The result suggests how the cool down of the hot gas is avoided and why clusters look like they do.
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The XRISM science team, including members of Nagoya University, has explained how galaxy clusters maintain their heat despite emitting X-rays, which typically have a cooling effect on the hot gas. By observation of the Centaurus cluster of galaxies, the XRISM team discovered the existence of a fast-moving, high-temperature gas flow in the center of the cluster. Their findings, published by Nature, may solve the 'cooling flow problem', explaining why clusters of galaxies look like they do.
Galaxy clusters are made of hundreds of galaxies and are the largest objects in the universe. The clusters are important for studying the large-scale structure of the universe and understanding how galaxies (including our own) live, grow, and evolve.
Clusters are governed by a massive dark matter halo, the strong gravity of which attracts high-temperature gas from the intergalactic space outside the cluster. In the process, the hot gases emit X-rays, which have a cooling effect. As matter cools, it tends to condense and fall towards the center of the cluster and create stars. Although such star formation is seen, the amount is much smaller than expected and the center of galaxy clusters is unexpectedly warm, suggesting that the temperature is maintained by some mechanism that compensates for the 'cooling' effect.
The research team conducted observations of the Centaurus cluster of galaxies, which is located approximately 150 million light-years from Earth. The team used a soft X-ray spectrometer 'Resolve' onboard the XRISM satellite to accurately measure the detailed velocity of the flow of high-temperature gas in the center of the galaxy cluster. This flow supplies energy to its center and maintains the high temperature.
"We found little turbulence of the high-temperature gas in the galaxy cluster," Professor Nakazawa said. "The mechanism, which stops the cooling of the hot gas of this cluster, is a general 'stirring' of the hot gas that supplies energy to the center from outside regions, thus maintaining the high temperature."
Computer simulations of the movement of hot gas after the merging of clusters of galaxies that happened during their growth process were used to explain these motions, which is called 'gas sloshing.'
"High-precision spectroscopy will also help us to better understand how the massive structure of galaxy clusters evolves," Nakazawa said. "It deepens our understanding not only of galaxy clusters, but also of the formation and evolution of large-scale structures in the universe as a whole."
Story Source:
Materials provided by Nagoya University. Note: Content may be edited for style and length.
Journal Reference:
- Marc Audard, Hisamitsu Awaki, Ralf Ballhausen, Aya Bamba, Ehud Behar, Rozenn Boissay-Malaquin, Laura Brenneman, Gregory V. Brown, Lia Corrales, Elisa Costantini, Renata Cumbee, Chris Done, Tadayasu Dotani, Ken Ebisawa, Megan E. Eckart, Dominique Eckert, Teruaki Enoto, Satoshi Eguchi, Yuichiro Ezoe, Adam Foster, Ryuichi Fujimoto, Yutaka Fujita, Yasushi Fukazawa, Kotaro Fukushima, Akihiro Furuzawa, Luigi Gallo, Javier A. García, Liyi Gu, Matteo Guainazzi, Kouichi Hagino, Kenji Hamaguchi, Isamu Hatsukade, Katsuhiro Hayashi, Takayuki Hayashi, Natalie Hell, Edmund Hodges-Kluck, Ann Hornschemeier, Yuto Ichinohe, Manabu Ishida, Kumi Ishikawa, Yoshitaka Ishisaki, Jelle Kaastra, Timothy Kallman, Erin Kara, Satoru Katsuda, Yoshiaki Kanemaru, Richard Kelley, Caroline Kilbourne, Shunji Kitamoto, Shogo Kobayashi, Takayoshi Kohmura, Aya Kubota, Maurice Leutenegger, Michael Loewenstein, Yoshitomo Maeda, Maxim Markevitch, Hironori Matsumoto, Kyoko Matsushita, Dan McCammon, Brian McNamara, François Mernier, Eric D. Miller, Jon M. Miller, Ikuyuki Mitsuishi, Misaki Mizumoto, Tsunefumi Mizuno, Koji Mori, Koji Mukai, Hiroshi Murakami, Richard Mushotzky, Hiroshi Nakajima, Kazuhiro Nakazawa, Jan-Uwe Ness, Kumiko Nobukawa, Masayoshi Nobukawa, Hirofumi Noda, Hirokazu Odaka, Shoji Ogawa, Anna Ogorzalek, Takashi Okajima, Naomi Ota, Stephane Paltani, Robert Petre, Paul Plucinsky, Frederick Scott Porter, Katja Pottschmidt, Kosuke Sato, Toshiki Sato, Makoto Sawada, Hiromi Seta, Megumi Shidatsu, Aurora Simionescu, Randall Smith, Hiromasa Suzuki, Andrew Szymkowiak, Hiromitsu Takahashi, Mai Takeo, Toru Tamagawa, Keisuke Tamura, Takaaki Tanaka, Atsushi Tanimoto, Makoto Tashiro, Yukikatsu Terada, Yuichi Terashima, María Díaz Trigo, Yohko Tsuboi, Masahiro Tsujimoto, Hiroshi Tsunemi, Takeshi G. Tsuru, Hiroyuki Uchida, Nagomi Uchida, Yuusuke Uchida, Hideki Uchiyama, Yoshihiro Ueda, Shinichiro Uno, Jacco Vink, Shin Watanabe, Brian J. Williams, Satoshi Yamada, Shinya Yamada, Hiroya Yamaguchi, Kazutaka Yamaoka, Noriko Y. Yamasaki, Makoto Yamauchi, Shigeo Yamauchi, Tahir Yaqoob, Tomokage Yoneyama, Tessei Yoshida, Mihoko Yukita, Irina Zhuravleva, Marie Kondo, Norbert Werner, Tomáš Plšek, Ming Sun, Kokoro Hosogi, Anwesh Majumder. The bulk motion of gas in the core of the Centaurus galaxy cluster. Nature, 2025; 638 (8050): 365 DOI: 10.1038/s41586-024-08561-z
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