Suppression of black-hole growth by strong outflows at redshifts 5.8-6.6

Article

关键词: BROAD-ABSORPTION-LINE;    NEAR-INFRARED SPECTROSCOPY;    TO 6 QUASARS;    EMISSION-LINE;    INTRINSIC FRACTION;    DISCOVERY;    FEEDBACK;    CATALOG;    SAMPLE;    POPULATION;   

DOI  :  10.1038/s41586-022-04608-1

来源: SCIE

【 摘 要 】

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(1). How these black holes formed in such a short time isthe subject of debate, particularly asthey lie above the correlation between black-hole mass and galaxy dynamical mass(2,3) in the local Universe. What slowed down black-hole growth, leading towards the symbioticgrowth observed in the local Universe, and when this process started, has hitherto not been known, although black-hole feedback is a likely driver(4). Here we report optical and near-infrared observations of a sample of quasars at redshifts 5.8 less than or similar to z less than or similar to 6.6. About half ofthe quasar spectra reveal broad, blueshifted absorption line troughs, tracing black-hole-driven winds with extreme outflowvelocities, up to 17% of the speed of light. The fraction of quasars with such outflow winds at z greater than or similar to 5.8 approximate to 2.4 is times higher than at z approximate to 2-4. We infer that outflows at z greater than or similar to 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 greater than or similar to 5.8 indeed suggest that these systems are dusty and may be caught during an initial quenching phase of obscured accretion(5).

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