Fermi Gamma-ray Space Telescope

Cosmic-ray propagation models: 3D magnetic fields and induced interstellar emission in radio

Elena Orlando
Andrew Strong

Abstract:

Magnetic fields (B-fields) are responsible for cosmic-ray (CR) energy losses and diffusion in our Galaxy. Hence they affect interstellar emission from radio to gamma rays. Comparison of these emissions with models are the best way to characterize CRs. The problem is that the role of the strength and orientation of the B-fields has not been adequately accounted for when comparing Fermi-LAT data to models. This limitation came from our poor knowledge of the B-fields and the complexity in the modeling the emission. Nowadays the superb all-sky Fermi-LAT data call for a proper treatment of this issue. We present our recent extension of the GALPROP code to model 3D synchrotron emission both in temperature and polarization. We can now account for sophisticated 3D B-field models. We describe and show examples including realistic B-fields models for both regular and random components. Induced synchrotron emission in temperature and polarization is predicted and compared with present radio and microwave observations. Our recent results on regular and random B-fields, CR electrons spectra, and their propagation and distribution in the Galaxy are presented.