NUSTAR unveils a heavily obscured low-luminosity active galactic nucleus in the luminous infrared galaxy NGC 6286.
RICCI C., BAUER F.E., TREISTER E., ROMERO-CANIZALES C., AREVALO P., IWASAWA K., PRIVON G.C., SANDERS D.B., SCHAWINSKI K., STERN D. and IMANISHI M.
Abstract (from CDS):
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 Nuclear Spectroscopic Telescope Array 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 (NH ≃(0.95-1.32) x 1024 cm–2) with a column density consistent with being Compton-thick (CT, log(NH/cm–2)≥ 24). The AGN in NGC 6286 has a low absorption-corrected luminosity (L_2-10 keV_ ∼ 3-20 x 1041 erg s–1) and contributes <=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 multiwavelength 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 AGNs in LIRGs that can only be detected by sensitive hard X-ray observations.
galaxies: active - galaxies: interactions - infrared: galaxies - X-rays: galaxies - X-rays: general