Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-54772
Bournaud, F; Dekel, A; Teyssier, R; Cacciato, M; Daddi, E; Juneau, S; Shankar, F (2011). Black hole growth and active galactic nuclei obscuration by instability-driven inflows in high-redshift disk galaxies fed by cold streams. Astrophysical Journal Letters, 741(2):L33.
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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 ~ 1, and isolated galaxy simulations capable of resolving the nuclear inflow down to the central parsec. We predict an average inflow rate ~10 M sun yr-1 through the disk of a 1011 M sun galaxy, with conditions representative of z ~ 2 stream-fed disks. The inflow rate scales with disk mass and (1 + z)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 >~ 10-3 of it needs to accrete onto a central black hole (BH), in order to obey the observed BH-bulge relation. A galaxy of 1011 M sun at z ~ 2 is expected to host a BH of ~108 M sun, accreting on average with moderate sub-Eddington luminosity L X ~ 1042-1043 erg s-1, accompanied by brighter episodes when dense clumps coalesce. We note that in rare massive galaxies at z ~ 6, the same process may feed ~109 M 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.
|Other titles:||Black Hole growth and AGN obscuration by instability-driven inflows in high-redshift disk galaxies fed by cold streams|
|Item Type:||Journal Article, refereed, original work|
|Communities & Collections:||07 Faculty of Science > Institute of Theoretical Physics|
|Deposited On:||18 Feb 2012 14:23|
|Last Modified:||09 Jun 2013 12:54|
|Publisher:||Institute of Physics Publishing|
|ISSN:||0004-637X (P) 1538-4357 (E)|
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