COEVOLUTION BETWEEN SUPERMASSIVE BLACK HOLES AND BULGES IS NOT VIA INTERNAL FEEDBACK REGULATION BUT BY RATIONED GAS SUPPLY DUE TO ANGULAR MOMENTUM DISTRIBUTION
COEVOLUTION BETWEEN SUPERMASSIVE BLACK HOLES AND BULGES IS NOT VIA INTERNAL FEEDBACK REGULATION BUT BY RATIONED GAS SUPPLY DUE TO ANGULAR MOMENTUM DISTRIBUTION
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DOI：
10.1088/2041-8205/805/1/l9
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发表时间：
2015-04
期刊：
影响因子：
--
通讯作者：
R. Cen
中科院分区：
文献类型：
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作者：
R. Cen
我们推断，如果没有物理微调，无论是超大质量黑洞（SMBHs）还是恒星凸起都无法自我调节，也无法通过赶走已经落下的冷气体来相互调节，从而产生我们观察到的它们之间的相关性。我们提出了一种替代方案，即观测到的SMBHs与凸起的质量比反映了落入气体的角动量分布，这样到达稳定吸积盘的质量是到达凸起区域的质量的一小部分，在宇宙时间尺度上平均。我们在没有活动星系核（AGN）反馈的情况下，使用高分辨率的大规模宇宙流体动力学模拟来测试这一场景，假设在凸起区域着陆的气体的角动量分布产生了一个Mestel盘，该盘得到了解决SMBHs Bondi半径的独立模拟的支持。在自由落体到亚秒差距区域吸积到SMBH的极低角动量气体与整体恒星形成率之间的质量比为0.1%-0.3%。这一比例随着红移的增加而增加到约2的范围内，这表明smbh与凸起的比例几乎与红移无关，随着红移而适度增加，这是一个可测试的预测。此外，具有高爱丁顿比的agn的占空比预计会随着红移而显著增加。最后，虽然发现SMBH和凸起在~ 30-150 Myr或更长时间尺度上共同演化，但有迹象表明，在更小的时间尺度上，SMBH的吸积和恒星形成可能不太相关。
We reason that without physical fine-tuning, neither the supermassive black holes (SMBHs) nor the stellar bulges can self-regulate or inter-regulate by driving away already fallen cold gas to produce the observed correlation between them. We suggest an alternative scenario where the observed mass ratios of the SMBHs to bulges reflect the angular momentum distribution of infallen gas such that the mass reaching the stable accretion disk is a small fraction of that reaching the bulge region, averaged over the cosmological timescales. We test this scenario using high-resolution, large-scale cosmological hydrodynamic simulations, without active galactic nucleus (AGN) feedback, assuming the angular momentum distribution of gas landing in the bulge region yields a Mestel disk that is supported by independent simulations resolving the Bondi radii of SMBHs. A mass ratio of 0.1%–0.3% between the very low angular momentum gas that free falls to the subparsec region to accrete to the SMBH and the overall star formation rate is found. This ratio is found to increase with increasing redshift to within a factor of ∼2, suggesting that the SMBH-to-bulge ratio is nearly redshift independent, with a modest increase with redshift, which is a testable prediction. Furthermore, the duty cycle of AGNs with high Eddington ratios is expected to increase significantly with redshift. Finally, while SMBHs and bulges are found to coevolve on ∼30–150 Myr timescales or longer, there is indication that on still smaller timescales, the SMBH accretion and star formation may be less correlated.