BLACK HOLE GROWTH AND ACTIVE GALACTIC NUCLEI OBSCURATION BY INSTABILITY-DRIVEN INFLOWS IN HIGH-REDSHIFT DISK GALAXIES FED BY COLD STREAMS
- CEA, IRFU, SAp, 91191 Gif-sur-Yvette (France)
- Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)
- Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
- Max-Planck-Instituet fuer Astrophysik, D-85748, Garching (Germany)
Disk galaxies at high redshift have been predicted to maintain high gas surface densities due to continuous feeding by intense cold streams leading to violent gravitational instability, transient features, and giant clumps. Gravitational torques between the perturbations drive angular momentum out and mass in, and the inflow provides the energy for keeping strong turbulence. We use analytic estimates of the inflow for a self-regulated unstable disk at a Toomre stability parameter Q {approx} 1, and isolated galaxy simulations capable of resolving the nuclear inflow down to the central parsec. We predict an average inflow rate {approx}10 M{sub Sun} yr{sup -1} through the disk of a 10{sup 11} M{sub Sun} galaxy, with conditions representative of z {approx} 2 stream-fed disks. The inflow rate scales with disk mass and (1 + z){sup 3/2}. It includes clump migration and inflow of the smoother component, valid even if clumps disrupt. This inflow grows the bulge, while only a fraction of {approx}> 10{sup -3} of it needs to accrete onto a central black hole (BH), in order to obey the observed BH-bulge relation. A galaxy of 10{sup 11} M{sub Sun} at z {approx} 2 is expected to host a BH of {approx}10{sup 8} M{sub Sun }, accreting on average with moderate sub-Eddington luminosity L{sub X} {approx} 10{sup 42}-10{sup 43} erg s{sup -1}, accompanied by brighter episodes when dense clumps coalesce. We note that in rare massive galaxies at z {approx} 6, the same process may feed {approx}10{sup 9} M{sub Sun} BH at the Eddington rate. High central gas column densities can severely obscure active galactic nuclei in high-redshift disks, possibly hindering their detection in deep X-ray surveys.
- OSTI ID:
- 22047370
- Journal Information:
- Astrophysical Journal Letters, Vol. 741, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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