TeV γ Rays from Photodisintegration and Daughter Deexcitation of Cosmic-Ray Nuclei

It is commonly assumed that high-energy γ rays are made via either purely electromagnetic processes or the hadronic process of pion production, followed by decay. We investigate astrophysical contexts where a third process (A^*) would dominate: namely, the photodisintegration of highly boosted nuclei followed by daughter deexcitation. Starburst regions such as Cygnus OB2 appear to be promising sites for TeV γ-ray emission via this mechanism. A unique feature of the A^* process is a sharp flattening of the energy spectrum below ∼10  TeV/(T/eV) for γ-ray emission from a thermal region of temperature T. The A^* mechanism described herein offers an important contribution to γ-ray astronomy in the era of intense observational activity.