SPT-CL J2215−3537: A Massive Starburst at the Center of the Most Distant Relaxed Galaxy Cluster
SPT-CL J2215−3537: A Massive Starburst at the Center of the Most Distant Relaxed Galaxy Cluster
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DOI：
10.3847/1538-4357/acc6c2
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发表时间：
2023-03
期刊：
影响因子：
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通讯作者：
M. Calzadilla;L. Bleem;M. McDonald;M. Gladders;A. Mantz;S. Allen;M. Bayliss;A. Eilers;B. Floyd-B.-Fl
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作者：
M. Calzadilla;L. Bleem;M. McDonald;M. Gladders;A. Mantz;S. Allen;M. Bayliss;A. Eilers;B. Floyd-B.-Fl
我们发现了最遥远的，动态松弛的冷核星系团SPT-CL J2215−3537（SPT 2215），以及它的中心最亮星系团星系（BCG），z = 1.16。利用新的X射线观测，我们证明了SPT 2215拥有一个强冷的核心，其中心冷却时间为2亿年（在10 kpc时），最大的星团内介质冷却速率为1900 ± 400 M yr−1。这种惊人的冷却可能是哈勃太空望远镜成像中观察到的延伸的恒星形成细丝的原因。基于新的分光光度数据，我们在BCG中检测到明亮的[O ii]发射，这意味着一个未被遮蔽的星星形成速率（SFR）为320−140+230 M yr−1。弱射电源（0.8 GHz时为2.0 ± 0.8 mJy）的检测表明来自活动星系核（AGN）的持续反馈，尽管隐含的喷流功率不到热气体冷却光度的一半，与冷却压倒加热一致。极端冷却和SFR的SPT 2215是罕见的已知冷核心集群，更值得注意的是，我们观察到这些在如此高的红移，当大多数集群仍然是动态扰动。这个星系团的高质量，加上它与高度孤立的BCG动态弛豫的事实，表明它是一个非常罕见的系统，必须在早期宇宙中非常迅速地形成。结合高SFR，SPT 2215可能是凤凰星系团的高z模拟物，可能提供对AGN反馈和大质量星系中星星形成的限制的深入了解。
We present the discovery of the most distant, dynamically relaxed cool core cluster, SPT-CL J2215−3537 (SPT2215), and its central brightest cluster galaxy (BCG) at z = 1.16. Using new X-ray observations, we demonstrate that SPT2215 harbors a strong cool core with a central cooling time of 200 Myr (at 10 kpc) and a maximal intracluster medium cooling rate of 1900 ± 400 M ⊙ yr−1. This prodigious cooling may be responsible for fueling the extended, star-forming filaments observed in Hubble Space Telescope imaging. Based on new spectrophotometric data, we detect bright [O ii] emission in the BCG, implying an unobscured star formation rate (SFR) of 320−140+230 M ⊙ yr−1. The detection of a weak radio source (2.0 ± 0.8 mJy at 0.8 GHz) suggests ongoing feedback from an active galactic nucleus (AGN), though the implied jet power is less than half the cooling luminosity of the hot gas, consistent with cooling overpowering heating. The extreme cooling and SFR of SPT2215 are rare among known cool core clusters, and it is even more remarkable that we observe these at such high redshift, when most clusters are still dynamically disturbed. The high mass of this cluster, coupled with the fact that it is dynamically relaxed with a highly isolated BCG, suggests that it is an exceptionally rare system that must have formed very rapidly in the early universe. Combined with the high SFR, SPT2215 may be a high-z analog of the Phoenix cluster, potentially providing insight into the limits of AGN feedback and star formation in the most massive galaxies.