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arXiv · 1601.05800

NuSTAR unveils a heavily obscured low-luminosity Active Galactic Nucleus in the Luminous Infrared Galaxy NGC 6286

C. Ricci·F. E. Bauer·E. Treister·C. Romero-Canizales·P. Arevalo·K. Iwasawa·G. C. Privon·D. B. Sanders·K. Schawinski·D. Stern·M. Imanishi
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Abstract

We report the detection of a heavily obscured Active Galactic Nucleus (AGN) in the luminous infrared galaxy (LIRG) NGC 6286, identified in a 17.5 ks NuSTAR observation. The source is in an early merging stage, and was targeted as part of our ongoing NuSTAR campaign observing local luminous and ultra-luminous infrared galaxies in different merger stages. NGC 6286 is clearly detected above 10 keV and, by including the quasi-simultaneous Swift/XRT and archival XMM-Newton and Chandra data, we find that the source is heavily obscured [$N_{\rm\,H}\simeq (0.95-1.32)\times 10^{24}\rm\,cm^{-2}$], with a column density consistent with being Compton-thick [CT, $\log (N_{\rm\,H}/\rm cm^{-2})\geq 24$]. The AGN in NGC 6286 has a low absorption-corrected luminosity ($L_{2-10\rm\,keV}\sim 3-20\times 10^{41}\rm\,erg\,s^{-1}$) and contributes $\lesssim$1\% to the energetics of the system. Because of its low-luminosity, previous observations carried out in the soft X-ray band ($<10$ keV) and in the infrared did not notice the presence of a buried AGN. NGC 6286 has multi-wavelength characteristics typical of objects with the same infrared luminosity and in the same merger stage, which might imply that there is a significant population of obscured low-luminosity AGN in LIRGs that can only be detected by sensitive hard X-ray observations.

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C. Ricci, F. E. Bauer, E. Treister, C. Romero-Canizales, P. Arevalo, K. Iwasawa, G. C. Privon, D. B. Sanders, K. Schawinski, D. Stern, M. Imanishi. 2016-01-21. NuSTAR unveils a heavily obscured low-luminosity Active Galactic Nucleus in the Luminous Infrared Galaxy NGC 6286. https://doi.org/10.3847/0004-637x%2F819%2F1%2F4

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