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Published October 20, 2014 | Submitted + Published
Journal Article Open

The NuSTAR View of Nearby Compton-thick Active Galactic Nuclei: The Cases of NGC 424, NGC 1320, and IC 2560

Abstract

We present X-ray spectral analyses for three Seyfert 2 active galactic nuclei (AGNs), NGC 424, NGC 1320, and IC 2560, observed by NuSTAR in the 3–79 keV band. The high quality hard X-ray spectra allow detailed modeling of the Compton reflection component for the first time in these sources. Using quasi-simultaneous NuSTAR and Swift/XRT data, as well as archival XMM-Newton data, we find that all three nuclei are obscured by Compton-thick material with column densities in excess of ~5 × 10^(24) cm^(−2), and that their X-ray spectra above 3 keV are dominated by reflection of the intrinsic continuum on Compton-thick material. Due to the very high obscuration, absorbed intrinsic continuum components are not formally required by the data in any of the sources. We constrain the intrinsic photon indices and the column density of the reflecting medium through the shape of the reflection spectra. Using archival multi-wavelength data we recover the intrinsic X-ray luminosities consistent with the broadband spectral energy distributions. Our results are consistent with the reflecting medium being an edge-on clumpy torus with a relatively large global covering factor and overall reflection efficiency of the order of 1%. Given the unambiguous confirmation of the Compton-thick nature of the sources, we investigate whether similar sources are likely to be missed by commonly used selection criteria for Compton-thick AGNs, and explore the possibility of finding their high-redshift counterparts.

Additional Information

© 2014 The American Astronomical Society. Received 2013 December 24; accepted 2014 August 14; published 2014 September 30. The authors thank the anonymous referee for useful comments which have improved the manuscript. M.B. acknowledges support from the International Fulbright Science and TechnologyAward. A.C. acknowledges support fromASI-INAF grant I/037/012/0-011/13. M.K. gratefully acknowledges support from Swiss National Science Foundation Grant PP00P2_138979/1. Thisworkwas supported under NASA contract No. NNG08FD60C, and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by theASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). This research made use of the XRT Data Analysis Software (XRTDAS), archival data, software and on-line services provided by the ASDC. This research has made use of NASA's Astrophysics Data System. Facilities: NuSTAR, Swift, XMM-Newton

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Published - 0004-637X_794_2_111.pdf

Submitted - 1408.5414v1.pdf

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August 22, 2023
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