UZH-Logo

Black hole growth and active galactic nuclei obscuration by instability-driven inflows in high-redshift disk galaxies fed by cold streams


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.

Abstract

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.

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.

Citations

95 citations in Web of Science®
17 citations in Scopus®
Google Scholar™

Altmetrics

Downloads

67 downloads since deposited on 18 Feb 2012
21 downloads since 12 months
Detailed statistics

Additional indexing

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 for Computational Science
Dewey Decimal Classification:530 Physics
Language:English
Date:November 2011
Deposited On:18 Feb 2012 13:23
Last Modified:05 Apr 2016 15:21
Publisher:Institute of Physics Publishing
ISSN:0004-637X (P) 1538-4357 (E)
Publisher DOI:10.1088/2041-8205/741/2/L33
Related URLs:http://arxiv.org/abs/1107.1483
Permanent URL: http://doi.org/10.5167/uzh-54772

Download

[img]
Preview
Content: Accepted Version
Filetype: PDF (Version 3)
Size: 344kB
View at publisher
[img]
Preview
Content: Accepted Version
Filetype: PDF (Version 2)
Size: 341kB
[img]
Preview
Content: Accepted Version
Filetype: PDF (Version 1)
Size: 340kB

TrendTerms

TrendTerms displays relevant terms of the abstract of this publication and related documents on a map. The terms and their relations were extracted from ZORA using word statistics. Their timelines are taken from ZORA as well. The bubble size of a term is proportional to the number of documents where the term occurs. Red, orange, yellow and green colors are used for terms that occur in the current document; red indicates high interlinkedness of a term with other terms, orange, yellow and green decreasing interlinkedness. Blue is used for terms that have a relation with the terms in this document, but occur in other documents.
You can navigate and zoom the map. Mouse-hovering a term displays its timeline, clicking it yields the associated documents.

Author Collaborations