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arXiv 0902.0363astro-ph.CO
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AEGIS:X射线AGN在z~1处相对于镓团簇的研究

AEGIS: The Clustering of X-ray AGN Relative to Galaxies at z~1

Alison L. Coil, Antonis Georgakakis, Jeffrey A. Newman, Michael C. Cooper, Darren Croton, Marc Davis, David C. Koo, E. S. Laird, K. Nandra, Benjamin J. Weiner, … 展开作者

Alison L. Coil, Antonis Georgakakis, Jeffrey A. Newman, Michael C. Cooper, Darren Croton, Marc Davis, David C. Koo, E. S. Laird, K. Nandra, Benjamin J. Weiner, Christopher N. A. Willmer, Renbin Yan

摘要:

我们在AEGIS场中测量了z=0.7-1.4的非类星体X射线活动星系核的成团现象。通过对113个钱德拉选定的活动星系核(对数L_X的中位数为42.8 erg s^-1)与约5,000个DEEP 2星系的互相关,我们发现X射线活动星系核符合幂律,其成团尺度长度为r_0=5.95 +/-0.90 h^-1 Mpc,斜率γ =1.66 +/-0.22。X射线活动星系核在z~1处具有与红色、静止和“绿色”过渡星系相似的成团幅度,并且比蓝色恒星形成星系明显更成团。X射线活动星系核的聚集强度主要取决于宿主星系的颜色;红色宿主星系的活动星系核比蓝色宿主星系的活动星系核明显更聚集,其相对偏差类似于红色到蓝色的DEEP 2星系。我们没有检测到依赖于光学亮度,X射线光度,或硬度比在这里探测的范围内的集群。我们发现的证据表明,星系托管X射线活动星系核更集群比一个样本的星系匹配联合光学颜色和星等分布。这意味着拥有X射线活动星系核的星系比没有X射线活动星系核的相同颜色和光度的星系更可能存在于群体和更大质量的暗物质晕中。与DEEP 2场中的光选类星体相比,我们发现z~1处的X射线活动星系核比光选类星体(具有2.6 sigma显著性)更加聚集,因此可能存在于更大质量的暗物质晕中。我们的研究结果是一致的星系经历类星体阶段,而在蓝色的云之前解决的红色序列与较低的光度X射线活动星系核,如果它们是相似的对象在不同的演化阶段。

英文摘要:

We measure the clustering of non-quasar X-ray AGN at z=0.7-1.4 in the AEGIS field. Using the cross-correlation of 113 Chandra-selected AGN, with a median log L_X=42.8 erg s^-1, with ~5,000 DEEP2 galaxies, we find that the X-ray AGN are fit by a power law with a clustering scale length of r_0=5.95 +/-0.90 h^-1 Mpc and slope gamma=1.66 +/-0.22. X-ray AGN have a similar clustering amplitude as red, quiescent and `green' transition galaxies at z~1 and are significantly more clustered than blue, star-forming galaxies. The X-ray AGN clustering strength is primarily determined by the host galaxy color; AGN in red host galaxies are significantly more clustered than AGN in blue host galaxies, with a relative bias that is similar to that of red to blue DEEP2 galaxies. We detect no dependence of clustering on optical brightness, X-ray luminosity, or hardness ratio within the ranges probed here. We find evidence for galaxies hosting X-ray AGN to be more clustered than a sample of galaxies with matching joint optical color and magnitude distributions. This implies that galaxies hosting X-ray AGN are more likely to reside in groups and more massive dark matter halos than galaxies of the same color and luminosity without an X-ray AGN. In comparison to optically-selected quasars in the DEEP2 fields, we find that X-ray AGN at z~1 are more clustered than optically-selected quasars (with a 2.6-sigma significance) and therefore likely reside in more massive dark matter halos. Our results are consistent with galaxies undergoing a quasar phase while in the blue cloud before settling on the red sequence with a lower-luminosity X-ray AGN, if they are similar objects at different evolutionary stages.

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