Faint AGN in z ≳ 6 Lyman-break galaxies powered by cold accretion and rapid angular momentum transport

摘要: We develop a radiation pressure-balanced model for the interstellar medium of high-redshift galaxies that describes many facets galaxy formation at z ≳ 6, including star rates and distributions gas accretion on to central black holes. first show vertical gravitational force in disc such is dominated by self-gravity supported pressure ionizing starlight gas. Constraining our reproduce UV luminosity function Lyman-break (LBGs), we limit available parameter space wind mass-loading factors one four times canonical value momentum-driven winds. then focus study exploring effects different angular momentum transport mechanisms galactic find driven torques, as from linear spiral waves or non-linear orbit crossings, can build up hole masses = 6 consistent with M–σ relation duty cycle unity, while mediated local viscosity an α-disc results negligible (BH) accretion. Both torque models produce X-ray emission active nuclei (AGN) LBGs excess estimated contribution high-mass binaries. Using recent analysis deep Chandra observations Cowie et al., already begin rule out most extreme regions space: inflow velocity through must either be less than per cent circular AGN substantially obscured. Moderately deeper future larger sample sizes will able probe more reasonable range obscuring geometries.