Astrophys. J., 814, 11 (2015/November-3)
A new sample of obscured AGNs selected from the XMM-Newton and AKARI surveys.
TERASHIMA Y., HIRATA Y., AWAKI H., OYABU S., GANDHI P., TOBA Y. and MATSUHARA H.
Abstract (from CDS):
We report a new sample of obscured active galactic nuclei (AGNs) selected from the XMM-Newton serendipitous source and AKARI point-source catalogs. We match X-ray sources with infrared (18 and 90 µm) sources located at to create a sample consisting of 173 objects. Their optical classifications and absorption column densities measured by X-ray spectra are compiled and study efficient selection criteria to find obscured AGNs. We apply the criteria (1) X-ray hardness ratio defined by using the 2-4.5 keV and 4.5-12 keV bands > -0.1 and (2) EPIC-PN count rate (CR) in the 0.2-12 keV to infrared flux ratio CR/ or CR/ where F18 and F90are infrared fluxes at 18 and 90 µm in Jy, respectively, to search for obscured AGNs. X-ray spectra of 48 candidates, for which no X-ray results have been published, are analyzed and X-ray evidence for the presence of obscured AGNs such as a convex shape X-ray spectrum indicative of absorption of ∼ 1022–24/cm2, a very flat continuum, or a strong Fe-K emission line with an equivalent width of is found in 26 objects. Six of them are classified as Compton-thick AGNs, and four are represented by either Compton-thin or Compton-thick spectral models. The success rate of finding obscured AGNs combining our analysis and the literature is 92% if the 18 µm condition is used. Of the 26 objects, 4 are optically classified as an H ii nucleus and are new ''elusive AGNs'' in which star formation activity likely overwhelms AGN emission in the optical and infrared bands.
galaxies: active - infrared: galaxies - X-rays: galaxies
VizieR on-line data:
<Available at CDS (J/ApJ/814/11): table1.dat table2.dat table3.dat table4.dat table5.dat refs.dat>
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