Mid- and Far-infrared Properties of a Complete Sample of Local Active Galactic Nuclei
Abstract
We investigate the mid- (MIR) to far-infrared (FIR) properties of a nearly complete sample of local active galactic nuclei (AGNs) detected in the Swift/Burst Alert Telescope (BAT) all-sky hard X-ray (14-195 keV) survey, based on the cross correlation with the AKARI infrared survey catalogs complemented by those with Infrared Astronomical Satellite and Wide-field Infrared Survey Explorer. Out of 135 non-blazer AGNs in the Swift/BAT nine-month catalog, we obtain the MIR photometric data for 128 sources either in the 9, 12, 18, 22, and/or 25 μm band. We find good correlation between their hard X-ray and MIR luminosities over three orders of magnitude (42 < log λL λ(9, 18 μm) < 45), which is tighter than that with the FIR luminosities at 90 μm. This suggests that thermal emission from hot dusts irradiated by the AGN emission dominate the MIR fluxes. Both X-ray unabsorbed and absorbed AGNs follow the same correlation, implying isotropic infrared emission, as expected in clumpy dust tori rather than homogeneous ones. We find excess signals around 9 μm in the averaged infrared spectral energy distribution from heavy obscured "new type" AGNs with small scattering fractions in the X-ray spectra. This could be attributed to the polycyclic aromatic hydrocarbon emission feature, suggesting that their host galaxies have strong starburst activities.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2012
- DOI:
- 10.1088/0004-637X/754/1/45
- arXiv:
- arXiv:1205.5032
- Bibcode:
- 2012ApJ...754...45I
- Keywords:
-
- galaxies: active;
- galaxies: nuclei;
- infrared: galaxies;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 14 pages, 8 figures, accepted for publication in ApJ