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arXiv 0909.0003astro-ph.CO
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合并偏差与类星体成团

On merger bias and the clustering of quasars

Silvia Bonoli, Francesco Shankar, Simon White, Volker Springel, Stuart Wyithe

摘要:

我们使用的大目录的晕千年模拟测试是否最近合并的晕表现出更强的大规模集群比其他晕相同的质量。这种效应有助于理解类星体在高红移时的强烈聚集现象。然而,我们发现在红移范围2 < z < 5内,最近合并的晕没有统计学上显著的过量偏差,最大质量的晕显示出至多~ 5%的过量偏差。我们还考虑从建立在千年模拟的半解析模型中提取的星系。在固定的恒星质量,我们发现一个额外的偏差~ 20-30%,最近合并的对象,随着恒星质量的增加而减少。事实上,最近合并的星系被发现在系统上比相同恒星质量的其他星系更大质量的晕占了这个信号的一半左右,对于高质量星系来说可能更多。大质量系统的弱合并偏差表明,合并驱动性质的物体,如类星体,与其他具有相同特征质量的物体相比,不会有显着不同的聚集。我们讨论了这些结果的解释聚类数据类星体的占空比,可见时间,并在黑洞主机质量关系的演变的影响。

英文摘要:

We use the large catalogues of haloes available for the Millennium Simulation to test whether recently merged haloes exhibit stronger large-scale clustering than other haloes of the same mass. This effect could help to understand the very strong clustering of quasars at high redshift. However, we find no statistically significant excess bias for recently merged haloes over the redshift range 2 < z < 5, with the most massive haloes showing an excess of at most ~5%. We also consider galaxies extracted from a semianalytic model built on the Millennium Simulation. At fixed stellar mass, we find an excess bias of ~ 20-30% for recently merged objects, decreasing with increasing stellar mass. The fact that recently-merged galaxies are found in systematically more massive haloes than other galaxies of the same stellar mass accounts for about half of this signal, and perhaps more for high-mass galaxies. The weak merger bias of massive systems suggests that objects of merger-driven nature, such as quasars, do not cluster significantly differently than other objects of the same characteristic mass. We discuss the implications of these results for the interpretation of clustering data with respect to quasar duty cycles, visibility times, and evolution in the black hole-host mass relation.

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