Speaker
Yang Ruizhi
Description
We use 5 years of Fermi-LAT data towards the Galactic centre giant molecular cloud complex, Sagittarius B, to test questions of how well-mixed the Galactic component of cosmic rays are and the level of the cosmic-ray sea in different parts of the Galaxy. We use dust-opacity maps from the Planck satellite to obtain independent methods for background subtraction, and an estimate for the mass of the region. We then present high-quality spectrum of γ-ray emission from 0.3 to 30 GeV, and obtain an estimate of the cosmic-ray spectrum from the region. We obtain an estimate of the mass of the region of 1.5 ± 0.2 × 107 M⊙ using the Planck data, which agrees well with molecular-line derived estimates for the same region. We find the the γ-ray flux from this region is well-fit with a cosmic-ray spectrum the same as that observed locally, with evidence of a small over-density at intermediate (1–10 GeV) energies. We conclude that the γ-ray and cosmic-ray spectrum in the region can be well-fit using a local cosmic-ray spectrum.
| Registration number following "ICRC2015-I/" | 92 |
|---|---|
| Collaboration | -- not specified -- |
Author
Co-authors
Dr
David Jones
(Department of Astrophysics/IMAPP, Radboud University)
Prof.
Felix Aharonian
(Max-Planck-Institut für Kernphysik)
