HAL will be down for maintenance from Friday, June 10 at 4pm through Monday, June 13 at 9am. More information
Skip to Main content Skip to Navigation
Journal articles

The growth efficiency of high-redshift black holes

Abstract : The observational evidence that Super-Massive Black Holes (M ∼ 109-10 M) are already in place less than 1 Gyr after the big bang poses stringent time constraints on the growth efficiency of their seeds. Among proposed possibilities, the formation of massive (∼103-6 M) seeds and/or the occurrence of super-Eddington (dot{M}>dot{M}_{Edd}) accretion episodes may contribute to the solution of this problem. In this work, using a set of astrophysically motivated initial conditions, we analytically and numerically investigate the accretion flow on to high-redshift (z ∼ 10) black holes to understand the physical requirements favouring rapid and efficient growth. Our model identifies a `feeding-dominated' accretion regime and a `feedback-limited' one, the latter being characterized by intermittent (duty cycles D ≲ 0.5) and inefficient growth, with recurring outflow episodes. We find that low-mass seeds (≲103-4 M) evolve in the feedback-limited regime, while more massive seeds (≳105-6 M) grow very rapidly as they are found in the feeding-dominated regime. In addition to the standard accretion model with a fixed matter-energy conversion factor (ɛ = 0.1), we have also explored slim disc models, appropriate for super-Eddington accretion, where radiation is trapped in the disc and the radiative efficiency is reduced (ɛ ≲ 0.04), which may ensure a continuous growth with dot{M} ≫ dot{M}_{Edd} (up to {∼ } 300 dot{M}_{Edd} in our simulations). Under these conditions, outflows play a negligible role and a black hole can accrete 80-100 per cent of the gas mass of the host halo (∼107 M) in ∼10 Myr, while in feedback-limited systems we predict that black holes can accrete only up to ∼15 per cent of the available mass.
Complete list of metadata

Contributor : Hal Sorbonne Université Gestionnaire Connect in order to contact the contributor
Submitted on : Thursday, April 28, 2022 - 11:13:23 AM
Last modification on : Thursday, May 12, 2022 - 6:22:03 PM


Publisher files allowed on an open archive



Fabio Pacucci, Marta Volonteri, Andrea Ferrara. The growth efficiency of high-redshift black holes. Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2015, 452, pp.1922-1933. ⟨10.1093/mnras/stv1465⟩. ⟨insu-03644864⟩



Record views


Files downloads