Fermi Gamma-ray Space Telescope

Adding time-dependence to the models of the Galactic interstellar gamma-ray emission

Gudlaugur Johannesson
(Igor Moskalenko & Troy Porter)


The GALPROP code has been under continuous development since 1997 and is now considered the standard modelling tool for studies of cosmic rays (CRs) in the interstellar medium of galaxies. It is used by major experimental collaborations and individual researchers world-wide to model the distributions of CRs and the related electromagnetic emissions. Examples include models of the interstellar gamma-ray emission used for analysis of Fermi-LAT data, synchrotron emission models used by the Planck collaboration, and the interpretation of the Voyager 1, PAMELA, and AMS-02 CR data covering the range from a few MeV/nucleon to TeV/nucleon. New 3D models recently developed for the interstellar gas and radiation field density distributions provide new opportunities to study effects associated with the structure of the Milky Way galaxy. How the CR intensities and corresponding gamma-ray intensities change with time as new CR sources appear while others are melting into the interstellar medium is an open question. We will show our latest results with the GALPROP code including the time evolution of interstellar emission at different energies. Understanding of the time evolution of the non-thermal interstellar emissions leads to a deeper insight into the processes defining our current Galactic environment.