Spectral Energy Distributions of Far-Infrared-Selected X-Ray Luminous AGN in Stripe 82
Abstract
We compiled Spectral Energy Distributions (SEDs) of 90 Herschel SPIRE-detected sources that are also luminous X-ray sources survey (LX > 1043 erg/s) in the Stripe 82X catalog and thus almost certainly AGN. All 90 AGN have spectroscopic redshifts or well-determined photometric redshifts. This is the largest statistically complete sample of luminous AGN with detections at both X-Ray (0.5-10 keV) and far-infrared wavelengths (λ > 100 μm). We used AGNFitter to characterize the multi-wavelength SEDs, which span the wavelength range from 500 μm to 12 Å (10 keV). All of the sources have strong infrared components that peak at roughly 50 μm, characteristic of thermal emission from warm dust with temperature ~50-100 K). In all cases the far-infrared emission outshines the SED components typically associated with AGN, namely, a big blue bump at 0.1-0.4 μm and hot dust (perhaps from an obscuring torus or disk) at 2-20 μm -- by factors of a few to as much as 50. The relative strength of the far-infrared component does not correlate strongly with the X-ray luminosity; however, AGN with the strongest warm dust emission have much weaker big blue bumps and/or hot dust components, as well as slightly lower values of LX, possibly indicating heavy obscuration. The mean SED for our sample is similar to that of warm ultra-luminous infrared galaxies (ULIRGs), which have previously been identified as a transition stage in the evolution of ULIRGs to optical QSOs. Further high-resolution imaging and spectroscopy of individual sources will be required to determine whether the strong far-infrared emission is primarily associated with dust on large scales or near the AGN.
- Publication:
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American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23324217U