Large-scale Galactic diffuse gamma rays observed with the Fermi Gamma-Ray Space Telescope

TL;DR

This paper reports on the initial analysis of gamma-ray data from the Fermi Telescope, revealing detailed insights into Galactic diffuse gamma-ray emission and its relation to cosmic rays and Galactic structure.

Contribution

It presents the first spectra and profiles of gamma-ray emission across the sky, comparing observations with models to improve understanding of cosmic rays and Galactic structure.

Findings

Good agreement with cosmic ray-based predictions at intermediate latitudes

Initial spectra and profiles of gamma-ray emission provided

Implications for understanding Galactic cosmic ray distribution

Abstract

The LAT instrument on the Fermi Gamma-Ray Space Telescope is performing an all-sky survey from 20 MeV to 300 GeV with unprecedented statistics and angular resolution. This is providing a wealth of new information on the non-thermal emission from the Galactic interstellar medium with implications for cosmic rays and Galactic structure. First results at intermediate latitudes have already shown good agreement with predictions based on direct measurements of cosmic rays, suggesting that at least the local (within about 1 kpc from the Sun) gamma-ray emission is understood. We will present the first spectra from regions over the sky using the LAT data, and profiles for selected energies. The aim here is to evaluate the agreement with the models and assess what we can expect to learn as this analysis matures.