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arXiv 0904.0256astro-ph.CO
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Chandra深场中X射线选择性AGN的空间分布：理论展望

The spatial distribution of X-ray selected AGN in the Chandra deep fields: a theoretical perspective

Federico Marulli, Silvia Bonoli, Enzo Branchini, Roberto Gilli, Lauro Moscardini, Volker Springel

备注：
12 pages, 6 figures. Accepted for publication in MNRAS
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摘要：

在超大质量黑洞及其宿主星系和暗物质晕的分级协同演化框架下，研究了X射线选择活动星系核的空间分布。为此，我们应用了Croton等人开发的模型。（2006）、De Lucia & Blazot（2007）和Marulli et al.（2008）的千禧年运行的输出，并获得了数百个实现过去的光锥，从中我们提取了逼真的模拟AGN目录，模仿钱德拉深场。我们发现，除了在通量<1 e-15 erg/cm^2/s的情况下，模型活动星系核的计数与观测值相当一致。该模型预测的空间两点关联函数在20 Mpc/h以内符合幂律关系，与观测结果吻合较好。我们的模型与Chandra深场北的活动星系核的相关长度r_0相匹配，但低估了Chandra深场南的相关长度r_0。在Gilli et al.（2005）中，当斜率固定为gamma = 1.4时，失配的统计显著性为2-2.5 sigma，这表明预测的宇宙方差在误差预算中占主导地位，可能无法解释活动星系核在两个场中的不同相关长度。虽然我们的结果是强大的AGN光变曲线的模型处方的变化，光度依赖的集群是敏感的不同的光变曲线模型。然而，无论考虑的模型，在我们的模拟领域的活动星系核集群的光度依赖似乎是弱于在真正的钱德拉领域。这种不匹配的重要性需要使用更大的数据集来确认。

英文摘要：

We study the spatial distribution of X-ray selected AGN in the framework of hierarchical co-evolution of supermassive black holes and their host galaxies and dark matter haloes. To this end, we have applied the model developed by Croton et al.(2006), De Lucia & Blaizot(2007) and Marulli et al.(2008) to the output of the Millennium Run and obtained hundreds of realizations of past light-cones from which we have extracted realistic mock AGN catalogues that mimic the Chandra deep fields. We find that the model AGN number counts are in fair agreement with observations, except at fluxes <1e-15 erg/cm^2/s. The spatial two-point correlation function predicted by the model is well described by a power-law relation out to 20 Mpc/h, in close agreement with observations. Our model matches the correlation length r_0 of AGN in the Chandra Deep Field North but underestimates it in the Chandra Deep Field South. When fixing the slope to gamma = 1.4, as in Gilli et al. (2005), the statistical significance of the mismatch is 2-2.5 sigma, suggesting that the predicted cosmic variance, which dominates the error budget, may not account for the different correlation length of the AGN in the two fields. While our results are robust to changes in the model prescriptions for the AGN lightcurves, the luminosity dependence of the clustering is sensitive to the different lightcurve models adopted. However, irrespective of the model considered, the luminosity dependence of the AGN clustering in our mock fields seems to be weaker than in the real Chandra fields. The significance of this mismatch needs to be confirmed using larger datasets.

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