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arXiv 1702.01762astro-ph.GAastro-ph.HEgr-qc
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动态测量的超大质量黑洞样本中的选择偏差:半解析星系形成模型中残差之间的标度关系和相关

Selection bias in dynamically-measured supermassive black hole samples: Scaling relations and correlations between residuals in semi-analytic galaxy formation models

Enrico Barausse, Francesco Shankar, Mariangela Bernardi, Yohan Dubois, Ravi K. Sheth

摘要:

最近的工作已经证实,根据与其宿主星系的恒星质量等全局性质的标度关系估计的超大质量黑洞的质量可能偏高。这可能是由于必须解决黑洞的引力影响范围,才能可靠地估计黑洞质量。我们重新审视这个问题,通过使用一个全面的星系演化半解析模型,自洽地演变超大质量黑洞从高红移种子通过气体吸积和合并,也包括AGN反馈。一旦调整到再现黑洞质量与速度色散的(平均)相关性,该模型就无法解释与恒星质量的相关性。这种行为与模型的参数无关,因此表明数据中存在内部不一致。预测的分布,特别是在低质量端,也比观察到的要宽得多。然而,如果包括选择效应,模型的预测往往与观察结果一致。我们还证明了局部标度关系的残差之间的相关性在约束活动星系核反馈模型时比标度关系本身更有效。事实上,我们发现,我们的半解析模型,而在明显的广泛协议的尺度关系时,占选择偏差,产生非常弱的相关性,在固定的恒星质量的残差,与观测形成鲜明对比。这个问题仍然存在时,改变活动星系核的反馈强度,也存在于流体动力学宇宙学模拟地平线-活动星系核,其中包括国家的最先进的活动星系核反馈处理的$z\sim 0$输出。这表明,目前的活动星系核反馈模型可能太弱,或者根本没有捕捉到黑洞对恒星速度色散的影响。

英文摘要:

Recent work has confirmed that the masses of supermassive black holes, estimated from scaling relations with global properties such as the stellar masses of their host galaxies, may be biased high. Much of this may be caused by the requirement that the gravitational sphere of influence of the black hole must be resolved for the black-hole mass to be reliably estimated. We revisit this issue by using a comprehensive galaxy evolution semi-analytic model, which self-consistently evolves supermassive black holes from high-redshift seeds via gas accretion and mergers, and also includes AGN feedback. Once tuned to reproduce the (mean) correlation of black-hole mass with velocity dispersion, the model is unable to also account for the correlation with stellar mass. This behaviour is independent of the model's parameters, thus suggesting an internal inconsistency in the data. The predicted distributions, especially at the low-mass end, are also much broader than observed. However, if selection effects are included, the model's predictions tend to align with the observations. We also demonstrate that the correlations between the residuals of the local scaling relations are more effective than the scaling relations themselves at constraining AGN feedback models. In fact, we find that our semi-analytic model, while in apparent broad agreement with the scaling relations when accounting for selection biases, yields very weak correlations between their residuals at fixed stellar mass, in stark contrast with observations. This problem persists when changing the AGN feedback strength, and is also present in the $z\sim 0$ outputs of the hydrodynamic cosmological simulation Horizon-AGN, which includes state-of-the-art treatments of AGN feedback. This suggests that current AGN feedback models may be too weak or are simply not capturing the effect of the black hole on the stellar velocity dispersion.

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