Bischetti M, Feruglio C, D'Odorico V, Arav N, Bañados E, Becker G, Bosman S E I, Carniani S, Cristiani S, Cupani G, Davies R, Eilers A C, Farina E P, Ferrara A, Maiolino R, Mazzucchelli C, Mesinger A, Meyer R A, Onoue M, Piconcelli E, Ryan-Weber E, Schindler J-T, Wang F, Yang J, Zhu Y, Fiore F
INAF - Osservatorio Astronomico di Trieste, Trieste, Italy.
IFPU - Institute for Fundamental Physics of the Universe, Trieste, Italy.
Nature. 2022 May;605(7909):244-247. doi: 10.1038/s41586-022-04608-1. Epub 2022 May 11.
Bright quasars, powered by accretion onto billion-solar-mass black holes, already existed at the epoch of reionization, when the Universe was 0.5-1 billion years old. How these black holes formed in such a short time is the subject of debate, particularly as they lie above the correlation between black-hole mass and galaxy dynamical mass in the local Universe. What slowed down black-hole growth, leading towards the symbiotic growth observed in the local Universe, and when this process started, has hitherto not been known, although black-hole feedback is a likely driver. Here we report optical and near-infrared observations of a sample of quasars at redshifts 5.8 ≲ z ≲ 6.6. About half of the quasar spectra reveal broad, blueshifted absorption line troughs, tracing black-hole-driven winds with extreme outflow velocities, up to 17% of the speed of light. The fraction of quasars with such outflow winds at z ≳ 5.8 is ≈2.4 times higher than at z ≈ 2-4. We infer that outflows at z ≳ 5.8 inject large amounts of energy into the interstellar medium and suppress nuclear gas accretion, slowing down black-hole growth. The outflow phase may then mark the beginning of substantial black-hole feedback. The red optical colours of outflow quasars at z ≳ 5.8 indeed suggest that these systems are dusty and may be caught during an initial quenching phase of obscured accretion.
由吸积到数十亿太阳质量黑洞上提供能量的明亮类星体，在宇宙再电离时期就已存在，那时宇宙年龄为0.5 - 10亿年。这些黑洞如何在如此短的时间内形成是一个争论的话题，特别是因为它们位于本地宇宙中黑洞质量与星系动力学质量的相关性之上。是什么减缓了黑洞的增长，导致了在本地宇宙中观察到的共生增长，以及这个过程何时开始，迄今为止尚不清楚，尽管黑洞反馈可能是一个驱动因素。在此，我们报告了红移5.8≲z≲6.6的类星体样本的光学和近红外观测结果。大约一半的类星体光谱显示出宽的、蓝移的吸收线谷，追踪着具有极高外流速度的黑洞驱动风，速度高达光速的17%。红移z≳5.8时具有这种外流风的类星体比例比红移z≈2 - 4时高约2.4倍。我们推断，红移z≳5.8时的外流将大量能量注入星际介质并抑制核气体吸积，减缓了黑洞的增长。外流阶段可能标志着大量黑洞反馈的开始。红移z≳5.8时外流类星体的红色光学颜色确实表明这些系统有尘埃，并且可能处于吸积被遮挡的初始淬灭阶段。
