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M.E. Nord (NRL / UNM), N.E. Kassim, T.J.W. Lazio (NRL)
In order to test Cosmic Ray (CR) electron production, diffusion, and aging models, constraints must be made on the 3-dimensional distribution of CR electron emissivity and energy. Historical CR tracers generally provide a line-of-sight integrated measurement of the CR emissivity. One must then account for Galactic structure in interpreting the observations. At low frequencies, HII regions become opaque and can be observed in absorption against the background Galactic CR emissivity. This measurement may be used to calculate the line of sight CR electron emissivity between the observer and the HII region. Many such observations have the potential to map out the 3-dimensional distribution of Galactic CR emissivity. We demonstrate the discovery of two such HII absorption features in the direction of the Galactic center.