Super-Eddington growth of the first black holes

Abstract

The formation and growth of the first super massive black holes (SMBHs) at z ~ 6 is a subject of intense debate. If black holes grow at their Eddington rates, they must start from high-mass seeds, (Mseed ~10^4 -10^5 Msun), formed by direct collapse of gasHere I will consider an alternative scenario where remnant of population III stars, (M ~ 100 Msun), can grow at super-Eddington rates via radiatively inefficient slim accretion disks. In Pezzulli et al., (MNRAS 2016), we use an improved version of the cosmological, data-constrained semi-analytic model GAMETE/QSODUST. We follow, for each progenitor present in the simulation, the evolution of nuclear BH, gas cooling, disk and bulge formation of their host galaxies together with the star formation, SNe/AGN feedback and chemical and dust enrichment. By adopting SDSS J1148+5251 at z=6.4 as a prototype of luminous z=6 quasars, we find that ~ 80% of the SMBH mass of J1148 is provided by super-Eddington gas accretion, which can be sustained down to z ~ 10 in dense, gas-rich environments, and the BH progenitors of the final SMBH evolve in symbiosis with their host galaxiesWe reproduce all the observed quantities of J1148, also predicting an AGN-driven mass outflow rate at z=6.4 broadly consistent with the radial profile inferred from CII observation by Cicone et al. 2015. Interestingly, find that ~20% of J1148 progenitors at z=7.1 have BH luminosities and masses comparable to ULAS J1120, suggesting that the most distant quasar ever observed may be one of the progenitors of J1148.