ESO 3060170: A Massive Fossil Galaxy Group with a Heated Gas Core?
ESO 3060170: A Massive Fossil Galaxy Group with a Heated Gas Core?
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ESO 3060170：具有加热气体核心的巨大化石星系群？
DOI：
10.1086/422801
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
S. Murray
中科院分区：
文献类型：
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作者：
Ming Sun;W. Forman;A. Vikhlinin;A. Vikhlinin;A. Hornstrup;C. Jones;S. Murray
我们结合钱德拉、XMM-牛顿和光学观测，对ESO 3060170星系群进行了详细的研究。该星系被发现是一个化石星系群。该群X射线发射由一个中心、致密、冷却的核心(半径为10kpc)和一个超出中心10kpc的等温介质组成。10到50 kpc(冷却半径)之间的区域与50到400 kpc之间的气体具有相同的温度，尽管10到50 kpc(2-6 Gyr)之间的气体冷却时间比哈勃时间短。因此，ESO 3060170群没有群大小的冷却核心。我们认为，该群冷核可能在过去曾被中央活动星系核(AGN)爆发加热过，而这个小而致密的冷核是先前冷却核的截断遗迹。钱德拉的观测还揭示了中心区域的各种X射线特征，包括一个“手指”，一种边缘状的特征，以及一个小的“尾巴”，所有这些都沿着南北轴排列，星系光和星系群的分布也是如此。所提出的活动星系核爆发可能会导致气体围绕中心“晃动”，并产生这些不对称的特征。观测到的到RVIR的平坦温度分布与最近数值模拟中预测的温度分布不一致。我们比较了ESO 3060170群和其他三个群的熵分布，发现了一个比只考虑激波加热的模拟所预测的更平坦的关系，S∝r~0.85.这直接证明了群中心中非引力过程的重要性。我们推导了RVIR内的质量剖面，发现ESO 3060170群是已知的最大的化石群[×1014M☉]。该体系的M/L比值在0.3rvir时约为150rvir，属正常。
We present a detailed study of the ESO 3060170 galaxy group, combining Chandra, XMM-Newton, and optical observations. The system is found to be a fossil galaxy group. The group X-ray emission is composed of a central, dense, cool core (10 kpc in radius) and an isothermal medium beyond the central 10 kpc. The region between 10 and 50 kpc (the cooling radius) has the same temperature as the gas from 50 to 400 kpc, although the gas cooling time between 10 and 50 kpc (2-6 Gyr) is shorter than the Hubble time. Thus, the ESO 3060170 group does not have a group-sized cooling core. We suggest that the group cooling core may have been heated by a central active galactic nucleus (AGN) outburst in the past and that the small, dense, cool core is the truncated relic of a previous cooling core. The Chandra observations also reveal a variety of X-ray features in the central region, including a "finger," an edgelike feature, and a small "tail," all aligned along a north-south axis, as are the galaxy light and group galaxy distribution. The proposed AGN outburst may cause gas to "slosh" around the center and produce these asymmetric features. The observed flat temperature profile to rvir is not consistent with the predicted temperature profile in recent numerical simulations. We compare the entropy profile of the ESO 3060170 group with those of three other groups and find a flatter relation than that predicted by simulations involving only shock heating, S ∝ r~0.85. This is direct evidence of the importance of nongravitational processes in group centers. We derive the mass profiles within rvir and find that the ESO 3060170 group is the most massive fossil group known [ × 1014 M☉]. The M/L ratio of the system, ~150 at 0.3rvir, is normal.