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20 April 2024 |
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Unveiling a Population of X-ray Non-Detected AGN | | J. L. Donley
; G. H. Rieke
; J. R. Rigby
; P. G. Perez-Gonzalez
; | | Date: |
28 Jul 2005 | | Subject: | astro-ph | | Abstract: | We define a sample of 27 radio-excess AGN in the Chandra Deep Field North by selecting galaxies that do not obey the radio/infrared correlation for radio-quiet AGN and star-forming galaxies. Approximately 60% of these radio-excess AGN are X-ray undetected in the 2 Ms Chandra catalog, even at exposures of > 1 Ms; 25% lack even 2-sigma X-ray detections. The absorbing columns to the faint X-ray-detected objects are 10^22 cm^-2 < N_H < 10^24 cm^-2, i.e., they are obscured but unlikely to be Compton thick. Using a local sample of radio-selected AGN, we show that a low ratio of X-ray to radio emission, as seen in the X-ray weakly- and non-detected samples, is correlated with the viewing angle of the central engine, and therefore with obscuration. Our technique can explore the proportion of obscured AGN in the distant Universe; the results reported here for radio-excess objects are consistent with but at the low end of the overall theoretical predictions for Compton-thick objects. | | Source: | arXiv, astro-ph/0507676 | | Services: | Forum | Review | PDF | Favorites | |
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