Spitzer IRAC Analysis of Extended Emission in Star Forming Regions

The data from the Spitzer Space Telescope Infrared Array Camera (IRAC) has provided invaluable insights in star formation. In addition to the identification and classification of young forming stars, IRAC photometry can be used to analyze extended emission seen in star forming regions. The location of shocked molecular hydrogen (H2) emission in IRAC photometric color space can be used to search for protostellar outflows and to probe the thermal conditions of the shocked gas in the flow. In this study we model the emission from UV excited fluorescent H2 and PAH grains in photo-dissociation regions (PDRs) and cal culate the resulting color space. We show that the density of a PDR is reflected in the color space along with the strength of the radiation field. Additionally, we find that color analysis can be used to distinguish between shocked and UV excited H2 emission