INFRARED SPECTRAL ENERGY DISTRIBUTIONS OF SEYFERT GALAXIES: SPITZER SPACE TELESCOPE OBSERVATIONS OF THE 12 μm SAMPLE OF ACTIVE GALAXIES

The mid-infrared spectral energy distributions (SEDs) of 83 active galaxies, mostly Seyfert galaxies, selected from the extended 12 mu m sample are presented. The data were collected using all three instruments, Infrared Array Camera (IRAC), Infrared Spectrograph (IRS), and Multiband Imaging Photometer for Spitzer (MIPS), aboard the Spitzer Space Telescope. The IRS data were obtained in spectral mapping mode, and the photometric data from IRAC and IRS were extracted from matched, 20 '' diameter circular apertures. The MIPS data were obtained in SED mode, providing very low-resolution spectroscopy (R similar to 20) between similar to 55 and 90 mu m in a larger, 20 '' x 30 '' synthetic aperture. We further present the data from a spectral decomposition of the SEDs, including equivalent widths and fluxes of key emission lines; silicate 10 mu m and 18 mu m emission and absorption strengths; IRAC magnitudes; and mid-far-infrared spectral indices. Finally, we examine the SEDs averaged within optical classifications of activity. We find that the infrared SEDs of Seyfert 1s and Seyfert 2s with hidden broad line regions (HBLRs, as revealed by spectropolarimetry or other technique) are qualitatively similar, except that Seyfert 1s show silicate emission and HBLR Seyfert 2s show silicate absorption. The infrared SEDs of other classes within the 12 mu m sample, including Seyfert 1.8-1.9, non-HBLR Seyfert 2 (not yet shown to hide a type 1 nucleus), LINER, and H Pi galaxies, appear to be dominated by star formation, as evidenced by blue IRAC colors, strong polycyclic aromatic hydrocarbon emission, and strong far-infrared continuum emission, measured relative to mid-infrared continuum emission.