From the first stars to the first black holes

Abstract

The growth of the first super massive black holes (SMBHs) at z > 6 is still a major challenge for theoretical models. If it starts from black hole (BH) remnants of Population III stars (light seeds with mass ∼ 100 M ) it requires super-Eddington accretion. An alternative route is to start from heavy seeds formed by the direct collapse of gas onto a ∼ 10 5 M BH. Here we investigate the relative role of light and heavy seeds as BH progenitors of the first SMBHs. We use the cosmological, data constrained semi-analytic model GAMETE/QSOdust to simulate several independent merger histories of z > 6 quasars. Using physically motivated prescriptions to form light and heavy seeds in the progenitor galaxies, we find that the formation of a few heavy seeds (between 3 and 30 in our reference model) enables the Eddington-limited growth of SMBHs at z > 6. This conclusion depends sensitively on the interplay between chemical, radiative and mechanical feedback effects, which easily erase the conditions that allow the suppression of gas cooling in the low metallicity gas (Z < Z cr and J LW > J cr ). We find that heavy seeds can not form if dust cooling triggers gas fragmentation above a critical dust-to-gas mass ratio (D D cr ). In addition, the relative importance of light and heavy seeds depends on the adopted mass range for light seeds, as this dramatically affects the history of cold gas along the merger tree, by both SN and AGN-driven winds.

Supermassive star formation via super competitive accretion in slightly metal-enriched clouds

“…Dijkstra et al 2008Dijkstra et al , 2014 to 10 −6 -10 −4 Mpc −3 (e.g. Agarwal et al 2012;Chon et al 2016;Habouzit et al 2016;Valiante et al 2016). Although those seeds can account for rare BHs in the high-z universe, they fail to be as abundant as all the SMBHs ubiquitously residing in massive galaxies, ∼ 0.01-0.1 Mpc −3 (Aller & Richstone 2002; Davis et al 2014).…”

Physical Properties of 15 Quasars at z ≳ 6.5

“…While the black hole seeds from Population III stars are expected to be relatively small (∼100 M e ; e.g., Valiante et al 2016), direct collapse of massive clouds can lead to the formation of more massive seeds ( 10 10 4 6 -M e ; for a review see Volonteri 2010). In general, the time in which a black hole of mass M BH,f is grown from an initial seed M BH,seed , assuming that it accretes with a constant Eddington ratio for all the time, can be written as Figure 9.…”

“…The current preferred models include the formation of black hole seeds from the direct collapse of massive gaseous reservoirs (e.g., Haehnelt & Rees 1993;Latif & Schleicher 2015), the collapse of Population III stars (e.g., Bond et al 1984;Alvarez et al 2009;Valiante et al 2016), the co-action of dynamical processes, gas collapse and star formation (e.g., Devecchi & Volonteri 2009), or the rapid growth of stellar-mass seeds via episodes of super-Eddington, radiatively inefficient accretion (e.g., Alexander & Natarajan 2014;Madau et al 2014;Pacucci et al 2015;Lupi et al 2016;Pezzulli et al 2016;Volonteri et al 2016;Begelman & Volonteri 2017 , assuming accretion at the Eddington limit and an efficiency of 10%; Volonteri & Rees 2005). For instance, in the seemingly short redshift range z 6.0 6.5 -, corresponding to ∼90 Myr, a black hole can grow by a factor of 6.…”

Theoretical re-evaluations of the black hole mass–bulge mass relation – I. Effect of seed black hole mass

“…In the second method, a seed BH of a fixed mass is placed immediately after a galaxy forms: 10 2 M⊙ (Menci et al 2003), 10 3 M⊙ (Fontanot et al 2015), or 10 5 M⊙ . For a deeper understanding of seed BHs from SA models, Pezzulli et al (2016) and Valiante et al (2016) focus on BH growth only in early universe (z 5) and suggest that 100 M⊙ seed BHs at z 23 accretes gas via major mergers at super-Eddington rates, forming 10…”