A three‐dimensional decomposition of the infrared emission from dust in the milky way

We have constructed a three‐dimensional model of the Galactic large‐scale infrared emission from dust associated with the molecular (H2), neutral atomic (H I), and extended low‐density ionized (H II) gas phases of the interstellar medium. The model incorporates a three‐dimensional map of the molecular and neutral atomic hydrogen gas distributions, derived from available 12CO and H I surveys by using the radial velocity information in the spectral lines as a distance indicator, and available 5 and 19 GHz radio‐continuum surveys to trace the column density of ionized gas. We have used the model to decompose the COBE Diffuse Infrared Background Experiment (DIRBE) 12–240 μm observations of the Galactic plane region (‖b‖<5°), from which the zodiacal‐light and stellar emission have been subtracted, into distinct emission components associated with each gas phase within selected ranges of galactocentric distance. An interstellar dust model was fit to the resulting far‐infrared spectra to derive the large‐scale p...