Speaker
Description
The current understanding of the diffuse gamma-ray emission, which is thought to be mainly produced by cosmic ray (CR) particles interacting with the interstellar gas and radiation fields, has a significant basis on advances made with the Fermi Large Area Telescope (Fermi-LAT) over the past decade of its operation. The Fermi-LAT observations are most sensitive at GeV gamma-ray energies, and trace the CRs that have been propagating millions of years through the Milky Way. The gamma-ray distribution on the sky measured by the Fermi-LAT is correspondingly broad and follows the line-of-sight integrated interstellar gas and radiation field densities. However, current generation very high energy instruments, like HESS and HAWC, probe CRs that have been recently accelerated and injected into the nearby interstellar medium (ISM). The corresponding distribution of gamma rays on the sky is more localised, tracing the CR and ISM densities nearby individual the sources. I will talk about recent modelling using the well-known GALPROP code to understand the links between the energy regions covered by these experiments.
