We present the observed-frame optical, near-, and mid-infrared properties of X-ray-selected active galactic nuclei (AGN) in the Lockman Hole. Using a likelihood ratio method on optical, near-infrared or mid-infrared catalogues, we assigned counterparts to 401 out of the 409 X-ray sources of the XMM-Newton catalogue. Accurate photometry was collected for all the sources from U to 24 μm. We used X-ray and optical criteria to remove any normal galaxies, galactic stars, or X-ray clusters among them and studied the multi-wavelength properties of the remaining 377 AGN. We used a mid-IR colour-colour selection to understand the AGN contribution to the optical and infrared emission. Using this selection, we identified different behaviours of AGN-dominated and host-dominated sources in X-ray-optical-infrared colour-colour diagrams. More specifically, the AGN-dominated sources show a clear trend in the f x/fRC vs. RC - K and f24 μm /fRC vs. RC - K diagrams, while the hosts follow the behaviour of non X-ray detected galaxies. In the optical-near- infrared colour-magnitude diagram we see that the known trend of redder objects to be more obscured in X-rays is stronger for AGN-dominated than for host-dominated systems. This is an indication that the trend is more related to the AGN, which contaminate the overall colours, than to any evolutionary effects. Finally, we find that a significant fraction (∼30%) of the reddest AGN are not obscured in X-rays.
|Original language||English (US)|
|Journal||Astronomy and astrophysics|
|State||Published - 2011|
- Galaxies: Seyfert
- Galaxies: active
- Galaxies: statistics
- Infrared: galaxies
- X-rays: galaxies
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
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AGN Opt/IR properties in Lockman Hole
Rovilos, E. (Creator), Fotopoulou, S. (Creator), Salvato, M. (Creator), Burwitz, V. (Creator), Egami, E. (Creator), Hasinger, G. (Creator) & Szokoly, G. (Creator), Centre de Donnees Strasbourg (CDS), 2011
DOI: 10.26093/cds/vizier.35290135, https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/529/A135