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تسجيل مستخدم جديدThe composite nature of Dust-Obscured Galaxies (DOGs) at z~2-3 in the COSMOS field: II. The AGN fraction
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We present the X-ray properties of 108 Dust-Obscured Galaxies (DOGs; F$_{24 mu m}$/F$_{R} >$ 1000) in the COSMOS field, all of which detected in at least three far-infrared bands with the Herschel Observatory. Out of the entire sample, 22 are individually detected in the hard 2-8 keV X-ray band by the Chandra COSMOS Legacy survey, allowing us to classify them as AGN. Of them, 6 (27%) are Compton Thick AGN candidates with column densities N$_{H}$$>$10$^{24}$ cm$^{-2}$ while 15 are moderately obscured AGNs with 10$^{22}$ $<$ N$_{H}$ $<$ 10$^{24}$ cm$^{-2}$. Additionally, we estimate AGN contributions to the IR luminosity (8-1000$mu$m rest-frame) greater than 20% for 19 DOGs based on SED decomposition using Spitzer/MIPS 24$mu$m and the five Herschel bands (100-500 $mu$m). Only 7 of these are detected in X-rays individually. We performed a X-ray stacking analysis for the 86 undetected DOGs. We find that the AGN fraction in DOGs increases with 24$mu$m flux and that it is higher than that of the general 24$mu$m population. However, no significant difference is found when considering only X-ray detections. This strongly motivates the combined use of X-ray and far-IR surveys to successfully probe a wider population of AGNs, particularly for the most obscured ones.
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Dust-Obscured galaxies (DOGs) are bright 24 um-selected sources with extreme obscuration at optical wavelengths. They are typically characterized by a rising power-law continuum of hot dust (T_D ~ 200-1000K) in the near-IR indicating that their mid-I
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A simple mid-infrared-to-optical color criterion of R-[24]>14 Vega mag results in a robust selection of approximately half of the redshift 2 ultraluminous infrared galaxy (ULIRG) population. These `Dust-Obscured Galaxies, or DOGs, have many propertie
s that suggest that they are good candidates for systems in a transition phase between gas-rich mergers and QSOs.
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