The spectral energy distributions and the bolometric luminosities of local AGN: study of the complete 12 micron AGN sample

Abstract

We measure the bolometric luminosity of a complete and unbiased 12 micron-selected sample of active galactic nuclei (AGN) in the local Universe. For each galaxy we used a 10-band radio-to-X-ray Spectral Energy Distribution (SED) to isolate the genuine AGN continuum in each band, including sub-arcsecond measurements where available, and correcting those contaminated by the host galaxy. We derive the median SED of Seyfert type 1 AGN, Seyferts with hidden broad-lines (HBL), Seyferts of type 2, and LINER nuclei in our sample. The median Seyfert 1 SED shows the characteristic blue bump feature in the UV, but nevertheless the largest contribution to the bolometric luminosity comes from the IR and X-ray continua. The median SEDs of both HBL and type 2 AGN are affected by starlight contamination in the optical/UV. The median SED of HBL AGN is consistent with that of Seyfert 1's, when an extinction of Av = 1.2 mag is applied. The comprehensive SEDs allowed us to measure accurate bolometric luminosities and derive robust bolometric corrections for the different tracers. The 12 micron and the K-band nuclear luminosities have good linear correlations with the bolometric luminosity, similar to those in the X-rays. We derive bolometric corrections for either continuum bands (K-band, 12 micron, 2-10 keV and 14-195 keV) and narrow emission lines (mid-IR high ionization lines of [OIV] and [NeV] and optical [OIII]5007A) as well as for combinations of IR continuum and line emission. A combination of continuum plus line emission accurately predicts the bolometric luminosity up to quasar luminosities.