期刊
ASTROPHYSICAL JOURNAL
卷 668, 期 1, 页码 81-86出版社
IOP PUBLISHING LTD
DOI: 10.1086/520874
关键词
galaxies : Seyfert; X-rays : general
资金
- Science and Technology Facilities Council [PP/D001013/1] Funding Source: researchfish
- STFC [PP/D001013/1] Funding Source: UKRI
For a significant number of the sources detected at high energies (> 10 keV) by the INTEGRAL IBIS and Swift BAT instruments there is either a lack information about them in the 2-10 keVrange or they are totally unidentified. Herein, we report on a sample of 34 IBIS AGNs or AGN candidate objects for which there is X-ray data in the Swift XRT archive. Thanks to these X-ray follow-up observations, the identification of the gamma-ray emitters has been possible and the spectral shape in terms of photon index and absorption has been evaluated for the first time for the majority of our sample sources. The sample, enlarged to include four more AGNs already discussed in the literature, has been used to provide photon index and column density distribution. We obtain a mean value of 1.88with a dispersion of 0.12, i. e., typical of anAGNsample. Sixteen objects (47%) have column densities in excess of 10(22) cm(-2) and, as expected, a large fraction of the absorbed sources are within the Sey 2 sample. We have provided a new diagnostic tool (N-H vs. F2-10 keV/F20-100 keV softness ratio) to isolate peculiar objects; we find at least one absorbed Sey 1 galaxy, three Compton-thick AGN candidates; and one secure example of a true type 2 AGN. Within the sample of 10 still unidentified objects, 3 are almost certainly AGNs of type 2; 3-4 have spectral slopes typical of AGN; and 2 are located high on the Galactic plane and are strong enough radio emitters that they can be considered good AGN candidates.
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