Growing Supermassive Black Holes by Chaotic Accretion

Abstract

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 low radiative accretion efficiency. If, as was formerly thought, the black--hole spin aligns very rapidly with the accretion flow, even a randomly--oriented sequence of accretion events would all spin up the hole and prevent rapid mass growth. However, using a recent result that the Bardeen--Petterson effect causes {\it counter}alignment of hole and disc spins under certain conditions, we show that holes can grow rapidly in mass if they acquire most of it in a sequence of randomly oriented accretion episodes whose angular momenta $J_d$ are no larger than the hole's angular momentum $J_h$. Ultimately the hole has total angular momentum comparable with the last accretion episode. This points to a picture in which the accretion is chaotic on a lengthscale of order the disc size, that is $\la 0.1$ pc.

MNRAS, in press

References in corpus (12)

• HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
• Inflation after WMAP3: Confronting the Slow-Roll and Exact Power Spectra with CMB Data
• Inflation model constraints from the Wilkinson Microwave Anisotropy Probe three-year data
• An absolutely calibrated survey of polarized emission from the northern sky at 1.4 GHz
• Inflationary predictions for scalar and tensor fluctuations reconsidered
• High Galactic latitude polarized emission at 1.4 GHz and implications for cosmic microwave background observations
• Detectability of tensor modes in the presence of foregrounds
• An angular power spectrum analysis of the DRAO 1.4 GHz polarization survey: implications for CMB observations
• 1.4 GHz polarimetric observations of the two fields imaged by the DASI experiment
• Polarized Diffuse Emission at 2.3 GHz in a High Galactic Latitude Area
• Deep 1.4-GHz observations of diffuse polarized emission
• A statistical analysis of a Galactic all sky survey at 1.4 GHz

Cited by in corpus (6)

• Ultra-high-energy debris from the collisional Penrose process
• The Cosmic Microwave Background for Pedestrians: A Review for Particle and Nuclear Physicists
• Ringed accretion disks: evolution of double toroidal configurations
• CMB polarization constraints on radiative feedback
• The Parkes Galactic Meridian Survey (PGMS): observations and CMB polarization foreground analysis
• Accreting Black Holes