THE GLOBAL IMPLICATIONS OF THE HARD X-RAY EXCESS IN TYPE 1 ACTIVE GALACTIC NUCLEI
Journal Article
·
· Astrophysical Journal
- Department of Physics, University of Maryland Baltimore County, Baltimore, MD 21250 (United States)
- Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom)
Recent evidence for a strong 'hard excess' of flux at energies {approx}> 20 keV in some Suzaku observations of type 1 active galactic nuclei (AGNs) has motivated an exploratory study of the phenomenon in the local type 1 AGN population. We have selected all type 1 AGNs in the Swift Burst Alert Telescope 58 month catalog and cross-correlated them with the holdings of the Suzaku public archive. We find the hard excess phenomenon to be a ubiquitous property of type 1 AGNs. Taken together, the spectral hardness and equivalent width of Fe K{alpha} emission are consistent with reprocessing by an ensemble of Compton-thick clouds that partially cover the continuum source. In the context of such a model, {approx}80% of the sample has a hardness ratio consistent with >50% covering of the continuum by low-ionization, Compton-thick gas. A more detailed study of the three hardest X-ray spectra in our sample reveal a sharp Fe K absorption edge at {approx}7 keV in each of them, indicating that blurred reflection is not responsible for the very hard spectral forms. Simple considerations place the distribution of Compton-thick clouds at or within the optical broad-line region.
- OSTI ID:
- 22167291
- Journal Information:
- Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 762; ISSN ASJOAB; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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