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arXiv 1409.6965astro-ph.COastro-ph.GA
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X射线标度关系从半导体到团簇的统一

Unifying X-ray Scaling Relations from Galaxies to Clusters

Michael E. Anderson, Massimo Gaspari, Simon D. M. White, Wenting Wang, Xinyu Dai

摘要:

我们研究了一个样本的$\sim 250 000$“本地最亮的星系”从斯隆数字巡天是中央星系内的暗物质晕。这些是普朗克合作组织以前堆叠的,以测量作为中央星系恒星质量函数的Sunyaev-Zel'dovich信号。在这里,我们使用来自ROSAT全天巡天的数据将这些光环的X射线发射叠加起来。我们几乎在整个样本中检测到发射,包括我们归因于星系周围的热气体的发射,这些星系的恒星质量范围从1.2 dex(相当于晕质量的近两个数量级)到$M* = 10^{10.8} M_{\odot}$($M_{500} \approx 10^{12.6} M_{\odot}$)。在这个范围内,X射线光度可以用恒星质量或晕质量的幂律拟合。质量和$L_X$之间的统一标度关系适用于星系、星系团和星系团。与$Y_{SZ}$ - $M_{500}$关系相反,这个关系比自相似性的预期斜率更陡,显示了非引力加热的重要性。如果这种加热主要是由于活动星系核的反馈,在我们的关系缺乏中断表明,活动星系核的反馈是严格的自我调节和相当温和的,在最近的高分辨率模拟协议。我们的结果与早期测量的$L_X$ - $L_K$关系的椭圆星系和$L_X$ - $M_{500}$关系的光学选择星系团是一致的。然而,我们的$L_X$ - $M_{500}$关系比基于X射线选择的聚类样本的大多数先前关系低两个因子以上。我们认为,光学选择提供了一个更少的$L_X$ - $M_{500}$关系的偏见。

英文摘要:

We examine a sample of $\sim 250 000$ "locally brightest galaxies" selected from the Sloan Digital Sky Survey to be central galaxies within their dark matter halos. These were previously stacked by the Planck Collaboration to measure the Sunyaev-Zel'dovich signal as a function of central galaxy stellar mass. Here, we stack the X-ray emission from these halos using data from the ROSAT All-Sky Survey. We detect emission across almost our entire sample, including emission which we attribute to hot gas around galaxies spanning a range of 1.2 dex in stellar mass (corresponding to nearly two orders of magnitude in halo mass) down to $M* = 10^{10.8} M_{\odot}$ ($M_{500} \approx 10^{12.6} M_{\odot}$). Over this range, the X-ray luminosity can be fit by a power-law, either of stellar mass or of halo mass. A single unified scaling relation between mass and $L_X$ applies for galaxies, groups, and clusters. This relation has a steeper slope than expected for self-similarity, in contrast to the $Y_{SZ}$-$M_{500}$ relation, showing the importance of non-gravitational heating. If this heating is predominantly due to AGN feedback, the lack of a break in our relation suggests that AGN feedback is tightly self-regulated and fairly gentle, in agreement with recent high-resolution simulations. Our results are consistent with earlier measurements of the $L_X$-$L_K$ relation for elliptical galaxies and of the $L_X$-$M_{500}$ relation for optically-selected galaxy clusters. However, our $L_X$-$M_{500}$ relation lies more than a factor of two below most previous relations based on X-ray-selected cluster samples. We argue that optical selection offers a less biased view of the $L_X$-$M_{500}$ relation.

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