Probing Hadronic Processes in Blazars with MeV Gamma-rays

Dr. Maria Petropoulou

Princeton University

Blazars - active galactic nuclei with relativistic jets powered by accretion onto their central supermassive black hole and closely aligned to our line of sight - are the most powerful persistent sources of electromagnetic radiation in the Universe, with bolometric luminosities of ~1e43-1e48 erg/s. Traditionally, the broadband spectral energy distributions (SEDs) of blazars have been explained by emission processes of electrons accelerated to high energies (i.e. leptonic scenarios). Alternatively, the high-energy blazar emission can be explained by processes relevant to relativistic protons and nuclei that also give rise to high-energy neutrinos (i.e. leptohadronic scenarios). Although both classes of models provide generally a good description of the blazar SED, they make different predictions about the photon emission and polarization signal in the poorly explored MeV energy band. I will discuss how future MeV observations can be used to differentiate between leptonic and hadronic processes in blazars.