$R_{2500}$星系团和星系团热大气的普适熵分布
A Universal Entropy Profile for the Hot Atmospheres of Galaxies and Clusters within $R_{2500}$
摘要：
我们提出了40个早期型星系和110个星系团的大气气体熵分布，跨越几十年的晕质量，大气气体质量，射电喷流功率和星系类型。我们发现，在$\sim 0.1R_{2500}$的熵配置文件的低质量系统，包括椭圆星系，最亮的星系团，和螺旋星系，规模约为$K\propto R^{2/3}$。$\sim 0.1R_{2500}$之外的熵剖面比仅从引力坍缩中预期的$K \propto R^{1.1}$剖面略浅，表明活动星系核反馈的加热远远超出了中央星系。我们发现，$K\propto R^{2/3}$熵分布形状表明，热不稳定冷却平衡加热的内部冷却和自由落体的时间尺度接近一个恒定的比例。与中央星系团相比，椭圆星系的热大气具有更高的每个气体粒子的加热速率。这种过度加热可以解释为什么一些中央星系团星系正在形成恒星，而大多数早期类型的星系在数十亿年内没有经历过显著的恒星形成。我们证明了六个透镜星系和螺旋星系的熵分布符合$R^{2/3}$形式。星系团、巨型椭圆星系和螺旋星系中的中央星系之间的连续性表明，加热椭圆星系和最亮星系团的大气层的过程可能也在螺旋星系中活跃。
英文摘要：
We present atmospheric gas entropy profiles for 40 early type galaxies and 110 clusters spanning several decades of halo mass, atmospheric gas mass, radio jet power, and galaxy type. We show that within $\sim 0.1R_{2500}$ the entropy profiles of low-mass systems, including ellipticals, brightest cluster galaxies, and spiral galaxies, scale approximately as $K\propto R^{2/3}$. Beyond $\sim 0.1R_{2500}$ entropy profiles are slightly shallower than the $K \propto R^{1.1}$ profile expected from gravitational collapse alone, indicating that heating by AGN feedback extends well beyond the central galaxy. We show that the $K\propto R^{2/3}$ entropy profile shape indicates that thermally unstable cooling is balanced by heating where the inner cooling and free-fall timescales approach a constant ratio. Hot atmospheres of elliptical galaxies have a higher rate of heating per gas particle compared to central cluster galaxies. This excess heating may explain why some central cluster galaxies are forming stars while most early-type galaxies have experienced no significant star formation for billions of years. We show that the entropy profiles of six lenticular and spiral galaxies follow the $R^{2/3}$ form. The continuity between central galaxies in clusters, giant ellipticals, and spirals suggests perhaps that processes heating the atmospheres of elliptical and brightest cluster galaxies are also active in spiral galaxies.
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