Related papers: Galactic Gamma Ray Background from Interactions of…
Using the cosmic ray (CR) data available in the energy interval $(10 - 2 \times 10^{7})$ GeV/particle, we have calculated the profile of the primary $\gamma$-ray spectrum produced by the interaction of these CR with thermal nuclei of the…
An extensive program for the calculation of galactic cosmic-ray propagation has been developed. Primary and secondary nucleons, primary and secondary electrons, secondary positrons and antiprotons are included. Fragmentation and energy…
Precise gamma-ray emissivities from cosmic-ray interactions with interstellar gas have been recently derived using Fermi-LAT data, and used to constrain the local interstellar spectra of protons and leptons. We report on a continuing effort…
The isotropic gamma-ray background (IGRB), measured by the Fermi Large Area Telescope, is the result of several classes of extragalactic astrophysical sources. Those sources include blazars, start-forming galaxies and radio galaxies. Also,…
Diffuse $\gamma$-ray emission produced by the interaction of cosmic-ray particles with matter and radiation in the Galaxy can be used to probe the distribution of cosmic rays and their sources in different regions of the Galaxy. With its…
We show that the well-known discrepancy between the radial dependence of the Galactic cosmic ray (CR) nucleon distribution, as inferred most recently from EGRET observations of diffuse gamma-rays above 100 MeV, and of the most likely CR…
The $\gamma$-ray emission of star-forming (SF) galaxies is attributed to hadronic interactions of cosmic ray (CR) protons with the interstellar gas and contributions from CR electrons via bremsstrahlung and inverse Compton (IC) scattering.…
Recent results from the HESS gamma ray telescope have shown the presence of both a diffuse, extended, flux of gamma rays above ~0.4 TeV and discrete sources in and near the Galactic Centre. Here, we put forward a possible explanation in…
Recent observations of the Galactic center in high-energy gamma-rays (above 0.1TeV) have opened up new ways to study this region, from understanding the emission source of these high-energy photons to constraining the environment in which…
Recent observations of the diffuse Galactic gamma-ray emission by the Fermi-LAT satellite have shown significant deviations from models which assume the same diffusion properties for cosmic rays (CR) throughout the Galaxy. We explore the…
It has been indicated that low-luminosity active galactic nuclei (LLAGNs) are accelerating high-energy cosmic-ray (CR) protons in their radiatively inefficient accretion flows (RIAFs). If this is the case, Sagittarius A* (Sgr A*) should…
Observations of molecular clouds in the gamma ray domain provide us with a tool to study the distribution of cosmic rays in the Galaxy. This is because cosmic rays can penetrate molecular clouds, undergo hadronic interactions in the dense…
High-energy collisions of cosmic-ray nuclei with interstellar gas are believed to be the mechanism producing the majority of cosmic ray antiprotons. Due to the kinematics of the process they are created with a nonzero momentum; the…
We consider the rate of ionization of diffuse and molecular clouds in the interstellar medium by Galactic cosmic rays (GCR) in order to constrain its low energy spectrum. We extrapolate the GCR spectrum obtained from PAMELA at high energies…
Simulations of Galactic CR transport were performed with the software GALPROP, with the resulting gamma-ray flux calculated up to the PeV regime. The impact of altering parameters such as the number and distribution of CR sources, the…
The center of the our Galaxy is a region where very energetic phenomena take place. In particular powerful cosmic ray sources can be located in that region. The cosmic rays accelerated in these sources may interact with ambient protons…
Context: The relation between Galactic cosmic-ray electrons, magnetic fields and synchrotron radiation. Aims: We exploit synchrotron radiation to constrain the low-energy interstellar electron spectrum, using various radio surveys and…
Most of the celestial gamma rays detected by the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope originate from the interstellar medium when energetic cosmic rays interact with interstellar nucleons and photons.…
Dynamically, cosmic rays with energies above about one GeV/nucleon may be important agents of galaxy evolution. Their pressures compare with the thermal and magnetic ones impacting galactic gas accretion, fountains and galactic outflows,…
We present a novel interpretation of the $\gamma$-ray diffuse emission measured by Fermi-LAT and H.E.S.S. in the Galactic center (GC) region and the Galactic ridge (GR). In the first part we perform a data-driven analysis based on PASS8…