Related papers: Super-Critical Growth of Massive Black Holes from …
The rapid assembly of the massive black holes that power the luminous quasars observed at $z \sim 6-7$ remains a puzzle. Various direct collapse models have been proposed to head-start black hole growth from initial seeds with masses $\sim…
We investigate the physical conditions for the growth of intermediate mass seed black holes assumed to have formed from remnants of the first generation of massive stars. We follow the collapse of high-sigma halos with Tvir > 1e4 K using…
Mass accretion by black holes (BHs) is typically capped at the Eddington rate, when radiation's push balances gravity's pull. However, even exponential growth at the Eddington-limited e-folding time t_E ~ few x 0.01 billion years, is too…
We consider the problem of growing the largest supermassive black holes from stellar--mass seeds at high redshift. Rapid growth without violating the Eddington limit requires that most mass is gained while the hole has a low spin and thus a…
Super-Eddington accretion onto massive black hole seeds may be commonplace in the early Universe, where the conditions exist for rapid accretion. Direct collapse black holes are often invoked as a possible solution to the observation of…
Super-massive black holes weighing up to $\sim 10^9 \, \mathrm{M_{\odot}}$ are in place by $z \sim 7$, when the age of the Universe is $\lesssim 1 \, \mathrm{Gyr}$. This implies a time crunch for their growth, since such high masses cannot…
The discovery of supermassive black holes with masses $\gtrsim 10^9 M_\odot$ at redshifts $z\gtrsim 10$ challenges conventional formation scenarios based on baryonic accretion and mergers within the first few hundred million years. We…
The observational evidence that Super-Massive Black Holes ($M_{\bullet} \sim 10^{9-10} \, \mathrm{M_{\odot}}$) are already in place less than $1 \, \mathrm{Gyr}$ after the Big Bang poses stringent time constraints on the growth efficiency…
Supermassive black holes are probably present in the centre of the majority of the galaxies. There is a consensus that these exotic objects are formed by the growth of seeds either by accreting mass from a circumnuclear disk and/or by…
Models aiming to explain the formation of massive black hole seeds, and in particular the direct collapse scenario, face substantial difficulties. These are rooted in rather ad hoc and fine-tuned initial conditions, such as the simultaneous…
The origin of the supermassive black holes that power the most distant quasars observed is largely unknown. One hypothesis is that they grew rapidly from intermediate-mass seeds (~100 M_sun) left by the first stars. However, some previous…
Extremely massive black holes, with masses $M_{\rm BH} > 10^9 M_\odot$, have been observed at ever higher redshifts. These results create ever tighter constraints on the formation and growth mechanisms of early black holes. Here we show…
With the recent discoveries of massive and highly luminous quasars at high redshifts ($z\sim7$; e.g. Mortlock et al. 2011), the question of how black holes (BHs) grow in the early Universe has been cast in a new light. In order to grow BHs…
Short-lived intermittent phases of super-critical (super-Eddington) growth, coupled with star formation via positive feedback, may account for early growth of massive black holes (MBH) and coevolution with their host spheroids. We estimate…
The super-Eddington accretion onto intermediate seed BHs is a potential formation mode of supermassive black holes exceeding $10^9~M_\odot$ in the early universe. We here investigate how such rapid accretion may occur with finite amounts of…
The formation, accretion and growth of supermassive black holes in the early universe are investigated. The accretion rate ${\dot M}$ is calculated using the Bondi accretion rate onto black holes. Starting with initial seed black holes with…
We report on a calculation of the growth of the mass of supermassive black holes at galactic centers from dark matter and Eddington - limited baryonic accretion. Assuming that dark matter halos are made of fermions and harbor compact…
We review and discuss theoretical studies addressing the possibility of gas accretion onto black holes occurring at rates exceeding the Eddington limit. Our focus is on the applications to the growth of black hole seeds at high redshift. We…
It has been recently suggested that supermassive black holes at z = 5-6 might form from super-fast (\dot M > 10^4 Msun/yr) accretion occurring in unstable, massive nuclear gas disks produced by mergers of Milky-Way size galaxies.…
The validity of the hypothesis that the massive black holes in high redshift quasars grew from stellar-sized "seeds" is contingent on a seed's ability to double its mass every few ten million years. This requires that the seed accrete at…