Constraining the IMF using TeV gamma ray absorption

Abstract

Gamma rays of ~TeV energies from distant sources suffer attenuation due to pair production off of ~1 micron EBL photons. We may exploit this process in order to indirectly measure the EBL and constrain models of galaxy formation. Here, using semi-analytic models of galaxy formation, we examine how gamma ray absorption may be used as an indirect probe of the stellar initial mass function (IMF), although there is a degeneracy with dust modeling. We point out that with the new generation of gamma ray telescopes including STACEE, MAGIC, HESS, VERITAS, and Milagro, we should soon possess a wealth of new data and a new method for probing the nature of the IMF.