The Spatial Distribution of Stellar CO Absorption in M83

Abstract

Long-slit H- and K-band near-infrared spectra have been acquired through the bright nuclear starburst region in the nearby galaxy M83. The spatial distribution of the stellar CO 2-0 absorption band broadly resembles that of the 2 μm continuum emission and has a maximum depth consistent with a pure starburst population. The band strength deceases monotonically away from this location to a value consistent with that seen in the giant-dominated populations in ellipticals and the bulges of spiral galaxies. There is no significant variation in the ratio of H (CO 6-3) and K (CO 2-0) band equivalent widths, which argues against any significant dilution of the bands by hot dust. The CO depth and Brγ emission-line equivalent width are anticorrelated. Comparison with starburst evolutionary models indicates an age gradient across this central region.