The Mid‐Infrared Spectral Energy Distribution, Surface Brightness, and Color Profiles in Elliptical Galaxies

Abstract

We combine 2MASS data and Spitzer archival data to study the emission inmid-infrared passbands (1.2-24 μm) from a sample of 18 ellipticalgalaxies. In general the surface brightness distributions resemble deVaucouleurs profiles, indicating that most of the emission arises fromthe photospheres or circumstellar regions of red giant stars. Thespectral energy distribution peaks near the H band at 1.6 μm. Thehalf-light or effective radius has a pronounced minimum near the K band(2.15 μm) with a second, less consistent minimum in the 24 μmpassband. All sample-averaged radial color profiles, whereλi