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

Abstract

The mid-far-infrared spectral energy distributions (SEDs) of 83 active\ngalaxies, mostly Seyfert galaxies, selected from the extended 12 micron sample\nare presented. The data were collected using all three instruments, IRAC, IRS,\nand MIPS, aboard the Spitzer Space Telescope. The IRS data were obtained in\nspectral mapping mode, and the photometric data from IRAC and IRS were\nextracted from matched, 20 arcsec diameter circular apertures. The MIPS data\nwere obtained in SED mode, providing very low resolution spectroscopy (R ~ 20)\nbetween ~ 55 and 90 microns in a larger, 20 by 30 arcsec synthetic aperture. We\nfurther present the data from a spectral decomposition of the SEDs, including\nequivalent widths and fluxes of key emission lines; silicate 10 and 18 micron\nemission and absorption strengths; IRAC magnitudes; and mid-far infrared\nspectral indices. Finally, we examine the SEDs averaged within optical\nclassifications of activity. We find that the infrared SEDs of Seyfert 1s and\nSeyfert 2s with hidden broad line regions (HBLR, as revealed by\nspectropolarimetry or other technique) are qualitatively similar, except that\nSeyfert 1s show silicate emission and HBLR Seyfert 2s show silicate absorption.\nThe infrared SEDs of other classes with the 12 micron sample, including Seyfert\n1.8-1.9, non-HBLR Seyfert 2 (not yet shown to hide a type 1 nucleus), LINER and\nHII galaxies, appear to be dominated by star-formation, as evidenced by blue\nIRAC colors, strong PAH emission, and strong far-infrared continuum emission,\nmeasured relative to mid-infrared continuum emission.\n