Conveners
Diffuse Gamma Rays & Cosmic Rays: Parallel-4
- Isabelle Grenier
A handedness in the arrival directions of high-energy photons from outside our Galaxy can be related back to the helicity of the inter-galactic magnetic field. Previous estimates by Tashiro et al. (2014) showed a hint of a signal present in the photons observed by the Fermi Large Area Telescope (LAT). An update on the measurement of handedness in the arrival direction of photons observed by...
Standard models of the large-scale interstellar emission officially adopted so far for studies of the Fermi-LAT data are very uncertain and show some discrepancies with respect to the data especially in the inner Galaxy where the degeneracy with the various components is large, underlining the necessity of more realistic models.
We focus here on the large-scale Inverse Compton (IC) component...
An accurate estimate of the interstellar gas density distribution is crucial to understanding the interstellar medium (ISM) and Galactic cosmic rays (CRs). However, a significant amount of gas not traced properly by standard radio line surveys (``dark gas") has been preventing accurate measurement of the total neutral gas column density and CR intensity. To overcome this difficulty, we...
The identification of active PeVatrons, hadronic particle accelerators reaching the knee (at the energy of few PeV), is crucial to understand the origin of cosmic rays in the Galaxy. In this context, we report on new H.E.S.S. observations of the PeVatron candidate HESSJ1702-420, close to the source 2FHL J1703.4-4145, that have revealed the presence of gamma-rays up to 100 TeV at 5 sigma...
The Large Area Telescope onboard the Fermi Gamma-ray Space Telescope has collected more than 15 millions of cosmic-ray electron and positron (CRE) events in the energy range from 42 GeV to 2 TeV in about 7.5 years since its launch in 2008. We have searched for possible features in the energy spectrum of Galactic CREs, which could be interpreted as a signature of the presence of a nearby dark...
Despite the enormous efforts done in very recent years, both theoretically and experimentally, the basic three questions about the CR origin remain without clear answers: what are their sources, how are they accelerated, how do they propagate?
Gamma-ray astronomy plays a fundamental role in this field. Both relativistic protons and electrons can emit in the gamma-ray band with different...
