2014/02/03 by Ruizhi Yang, Rui-zhi Yang, F. Aharonian +3
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Bubble #Cosmic ray #Dark Matter and Cosmic Phenomena #Fermi Gamma-ray Space Telescope #Gamma-ray bursts and supernovae #Hadron #Latitude #Longitude #Mechanics #Nuclear physics #Phenomenology (philosophy) #Physics #Population #Sky #astro-ph.HE
paper · pdf · doi:10.1051/0004-6361/201423562
8 pages. 9 figures. Submitted to Astronomy & Astrophysics
arxiv created 2014/02/03 · openalex publication_date 2014/04/28 · arxiv updated 2014/07/09 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We analyze 60 months of all-sky data from the Fermi-LAT. The Fermi bubble structures discovered previously are clearly revealed by our analysis. With more data, hence better statistics, we can now divide each bubble into constant longitude slices to investigate their gross γ-ray spectral morphology. While the detailed spectral behavior of each slice derived in our analysis is somewhat dependent on the assumed background model, we find, robustly, a relative deficit in the flux at low energies (i.e., hardening) toward the top of the south bubble. In neither bubble does the spectrum soften with longitude. The morphology of the Fermi bubbles is also revealed to be energy-dependent: at high energies they are more extended. We conclude from the gamma-ray spectrum at high latitudes that a low energy break in the parent cosmic ray population is required in both leptonic and hadronic models. We briefly discuss possible leptonic and hadronic interpretations of this phenomenology.