Interstellar molecules: from solid-state formation to gas-phase detection
Although one would expect molecules and atoms to be frozen out on dust grain surfaces at the low temperatures present in the Interstellar Medium (ISM), many species have actually been detected in the gas phase by astronomical observations. In this paper we study one way to release species into the gas phase, namely via the process of chemical desorption: evaporation caused by the excess energy of an exothermic reaction. Specific emphasis was put on the quantification of the process, in order for it to be implementable in astrochemical models that predict the molecular abundances in space.
Using a newly developed tool, SkyFACT, which is a hybrid approach between template fitting and image reconstruction, we study the gamma-ray emission from the Galactic Center. We find that the morphology of the so-called “Fermi-LAT Galactic Center Excess” is better described by the distribution of stars in the boxy bulge rather than the expected dark matter density squared. This supports the interpretation that this emission is due to millisecond pulsars instead of dark matter.