SIMBAD references

2005ApJ...634..169D - Astrophys. J., 634, 169-182 (2005/November-3)

Unveiling a population of AGNs not detected in X-rays.


Abstract (from CDS):

We define a sample of 27 radio-excess AGNs in the Chandra Deep Field-North by selecting galaxies that do not obey the radio/infrared correlation for radio-quiet AGNs and star-forming galaxies. Approximately 60% of these radio-excess AGNs are undetected in X-rays in the 2 Ms Chandra catalog, even at exposures of ≥1 Ms; 25% lack even 2 σ X-ray detections. The absorbing columns to the faint objects detected in X-rays are 1022/cm2<NH<1024/cm2; i.e., they are obscured but unlikely to be Compton-thick. Using a local sample of radio-selected AGNs, we show that a low ratio of X-ray to radio emission, as seen in the samples of AGNs weakly detected and undetected in X-rays, is correlated with the viewing angle of the central engine and therefore with obscuration. Our technique can explore the proportion of obscured AGNs 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.

Abstract Copyright:

Journal keyword(s): Galaxies: Active - Radio Continuum: Galaxies - X-Rays: Galaxies

Nomenclature: Table 1: [DRR2005] N=16+11.

Simbad objects: 40

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