标题： 利用钱德拉研究化石系统的核区域 显示英文标题

标题： Investigating the cores of fossil systems with Chandra

摘要： 我们利用存档的 *Chandra* 数据研究了化石星系团和星系群（“化石系统”）样本中的核心，该样本包含 17 个化石系统。 通过三个可观测诊断——中心冷却时间、尖度参数以及浓度参数——我们确定了化石系统的冷核分数。 我们通过 X 射线峰值与最亮的星系团星系 (BCG)，以及 X 射线峰值与发射加权中心之间的分离距离来量化化石系统的动力学状态。 我们研究了与 BCG 相关的 X 射线辐射，以探测热晕存在的可能性。 对于红移 z < 0.05 的化石系统，进行了去投影分析，以获得冷却时间和熵分布，并解析微妙的温度结构。 我们研究了来自 400d 星表的化石系统的 Lx-T 关系，以查看其比例关系是否偏离其他星系团。 大多数化石系统通过至少两种冷核诊断被识别为冷核对象。 所有化石系统的主导椭圆星系都在 X 射线峰值 50 千秒差距以内，且大多数的发射加权中心也位于此范围内。 与某些其他天体观测到的情况不同，我们没有发现明确的与 BCG 相关的 X 射线晕迹象。 化石系统并非具有普遍一致的温度分布，一些低温物体缺乏看似处于放松状态且具有冷核的星系所应具备的特征。 z < 0.05 的化石系统的熵分布可以用幂律模型很好地描述，尽管指数小于 1。 400d 星表中的化石系统 Lx-T 关系显示出相对于其他星系团更高的归一化值，这种趋势似乎在考虑选择效应后仍然存在。 显示英文摘要

摘要： We investigate the cores of fossil galaxy groups and clusters (`fossil systems') using archival Chandra data for a sample of 17 fossil systems. We determined the cool-core fraction for fossils via three observable diagnostics, the central cooling time, cuspiness, and concentration parameter. We quantified the dynamical state of the fossils by the X-ray peak/brightest cluster galaxy (BCG), and the X-ray peak/emission weighted centre separations. We studied the X-ray emission coincident with the BCG to detect the presence of potential thermal coronae. A deprojection analysis was performed for z < 0.05 fossils to obtain cooling time and entropy profiles, and to resolve subtle temperature structures. We investigated the Lx-T relation for fossils from the 400d catalogue to see if the scaling relation deviates from that of other groups. Most fossils are identified as cool-core objects via at least two cool-core diagnostics. All fossils have their dominant elliptical galaxy within 50 kpc of the X-ray peak, and most also have the emission weighted centre within that distance. We do not see clear indications of a X-ray corona associated with the BCG unlike that has been observed for some other objects. Fossils do not have universal temperature profiles, with some low-temperature objects lacking features that are expected for ostensibly relaxed objects with a cool-core. The entropy profiles of the z < 0.05 fossil systems can be well-described by a power law model, albeit with indices smaller than 1. The 400d fossils Lx-T relation shows indications of an elevated normalisation with respect to other groups, which seems to persist even after factoring in selection effects.