Astronomy and Astrophysics – Astrophysics
Scientific paper
2008-06-17
Astronomy and Astrophysics
Astrophysics
13 pages, 12 figures, 3 in color; accepted by ApJ
Scientific paper
10.1086/591048
We assess the potential of nuclear starburst disks to obscure the Seyfert-like AGN that dominate the hard X-ray background at z~1. Over 1200 starburst disk models, based on the theory developed by Thompson et al., are calculated for five input parameters: the black hole mass, the radial size of the starburst disk, the dust-to-gas ratio, the efficiency of angular momentum transport in the disk, and the gas fraction at the outer disk radius. We find that a large dust-to-gas ratio, a relatively small starburst disk, a significant gas mass fraction, and efficient angular momentum transport are all important to produce a starburst disk that can potentially obscure an AGN. The typical maximum star-formation rate in the disks is ~10 solar masses per year. Assuming no mass-loss due to outflows, the starburst disks feed gas onto the black hole at rates sufficient to produce hard X-ray luminosities of 10^{43}-10^{44} erg s^{-1}. The starburst disks themselves should be detectable at mid-infrared and radio wavelengths; at z=0.8, the predicted fluxes are ~1 mJy at 24microns and ~10-30 microJy at 1.4GHz. Thus, we predict a large fraction of radio/X-ray matches in future deep radio surveys. The starburst disks should be easily distinguished from AGN in future 100microns surveys by Herschel with expected fluxes of ~5 mJy. Any AGN-obscuring starbursts will be associated with hot dust, independent of AGN heating, resulting in observable signatures for separating galactic and nuclear star-formation. Finally, because of the competition between gas and star-formation, nuclear starbursts will be associated with lower-luminosity AGN. Thus, this phenomenon is a natural explanation for the observed decrease in the fraction of obscured AGN with luminosity.
No associations
LandOfFree
Obscuring Active Galactic Nuclei with Nuclear Starburst Disks does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Obscuring Active Galactic Nuclei with Nuclear Starburst Disks, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Obscuring Active Galactic Nuclei with Nuclear Starburst Disks will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-271795