Mid-Infrared Selection of Active Galaxies

摘要: Mid-infrared photometry provides a robust technique for identifying active galaxies. While the ultraviolet to mid-infrared (λ 5 μm) continuum of stellar populations is dominated by composite blackbody curve and peaks at approximately 1.6 μm, galactic nuclei (AGNs) power law. Consequently, with sufficient wavelength baseline, one can easily distinguish AGNs from populations. Mirroring tendency be bluer than galaxies in ultraviolet, where (and stars) sample blue, rising portion spectra, tend redder mid-infrared, red, falling spectra. We report on Spitzer Space Telescope colors, derived IRAC Shallow Survey, nearly 10,000 spectroscopically identified sources AGN Galaxy Evolution Survey. On basis this spectroscopic sample, we find that simple color criteria provide remarkably separation normal Galactic stars, over 80% completeness less 20% contamination. Considering only broad-lined AGNs, these identify 90% quasars Seyfert 1 Applying full imaging data set, discuss implied surface density evidence large population optically obscured