The growth of the gargantuan black holes powering high-redshift quasars and their impact on the formation of early galaxies and protoclusters

Abstract

High-redshift quasars (z ≳ 6), powered by black holes (BHs) with large inferred masses, imply rapid BH growth in the early Universe. The most extreme examples have inferred masses of ∼109 M⊙ at z = 7.5 and ∼1010 M⊙ at z = 6.3. Such dramatic growth via gas accretion likely leads to significant energy input into the quasar host galaxy and its surroundings, however few theoretical predictions of the impact of such objects currently exist. We present zoom-in simulations of a massive high-redshift protocluster, with our fiducial fable model incapable of reproducing the brightest quasars. With modifications to this model to promote early BH growth, such as earlier seeding and mildly super-Eddington accretion, such ‘gargantuan’ BHs can be formed. With this new model, simulated host dust masses and star formation rates are in good agreement with existing JWST and ALMA data from ultraluminous quasars. We find the quasar is often obscured as it grows, and that strong, ejective feedback is required to have a high probability of detecting the quasar in the rest-frame UV. Fast and energetic quasar-driven winds expel metal-enriched gas, leading to significant metal pollution of the circumgalactic medium (CGM) out to twice the virial radius. As central gas densities and pressures are reduced, we find weaker signals from the CGM in mock X-ray and Sunyaev-Zeldovich maps, whose detection - with proposed instruments such as Lynx, and even potentially presently with ALMA - can constrain quasar feedback.

A small and vigorous black hole in the early Universe

“…Many of these semi-analytical models and cosmological simulations could reproduce the mass of GN-z11 at z = 10.6 (refs. 7 , 25 – 27 ). The solid and dashed lines show the evolutionary tracks for some of them (described more extensively in the Methods ).…”

“…The horizontal grey-shaded regions indicate the range of black hole seeds expected by different scenarios. Solid and dashed lines indicate the evolutionary tracks of various simulations and models 7 , 25 , 35 that can reproduce the GN-z11 black hole mass, with different seeding and accretion rate assumptions, as detailed in the Methods . The small grey symbols indicate the black holes measured in quasars (QSOs) at z ≈ 6–7.5 (refs.…”

“… Several theories have been proposed to describe the formation of black hole seeds in the early Universe and to explain the emergence of very massive black holes observed in the first thousand million years after the Big Bang 1 – 3 . Models consider different seeding and accretion scenarios 4 – 7 , which require the detection and characterization of black holes in the first few hundred million years after the Big Bang to be validated. Here we present an extensive analysis of the JWST-NIRSpec spectrum of GN-z11, an exceptionally luminous galaxy at z = 10.6, revealing the detection of the [Ne iv ] λ 2423 and CII* λ 1335 transitions (typical of active galactic nuclei), as well as semi-forbidden nebular lines tracing gas densities higher than 10 9 cm −3 , typical of the broad line region of active galactic nuclei.…”

Which Came First: Supermassive Black Holes or Galaxies? Insights from JWST

“…In addition to triggering star formation, these can also lead to the compactification of gas clouds whose mergers provide sources of clumpy accretion in the nuclear environment. These may boost black hole growth via early super-Eddington accretion in massive halos (Bennett et al 2024).…”

Fueling Processes on (Sub-)kpc Scales

“…Simulations of black-hole growth with super-Eddington accretion, even in a massive over-density environment, progenitor of a cluster, in general, do not reproduce the observed massive black holes at z = 6 [38], nor explain why black-hole growth is more rapid than the stellar mass growth, contrary to what is observed at z = 0. However, with some modifications to the usual scenario, taking into account less efficient AGN feedback, more efficient accretion, and starting earlier with a more massive seed, it is possible to account for the observations [39].…”