Unveiling Obscured Accretion in the Chandra Deep Field-South
Abstract
We make use of deep HST, VLT, Spitzer, and Chandra data on the Chandra Deep Field-South to constrain the number of Compton-thick AGNs in this field. We show that sources with high 24 μm-to-optical flux ratios and red colors form a distinct source population, and that their infrared luminosity is dominated by AGN emission. Analysis of the X-ray properties of these extreme sources shows that most of them (80% +/- 15%) are indeed likely to be highly obscured, Compton-thick AGNs. The number of infrared-selected, Compton-thick AGNs with 5.8 μm luminosity higher than 1044.2 ergs s-1 turns out to be similar to that of X-ray-selected, unobscured, and moderately obscured AGNs with 2-10 keV luminosity higher than 1043 ergs s-1 in the redshift bin 1.2-2.6. This "factor of 2" source population is exactly what is needed to solve the discrepancies between model predictions and X-ray AGN selection.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2008
- DOI:
- 10.1086/523348
- arXiv:
- arXiv:0705.2864
- Bibcode:
- 2008ApJ...672...94F
- Keywords:
-
- galaxies: active;
- galaxies: high-redshift;
- X-rays: diffuse background;
- Astrophysics
- E-Print:
- Revised version, to be published by The Astrophysical Journal