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Several cosmic ray experiments have measured excesses in electrons and positrons, relative to standard backgrounds, for energies from ~ 10 GeV - 1 TeV. These excesses could be due to new astrophysical sources, but an explanation in which…

High Energy Astrophysical Phenomena · Physics 2014-11-20 Spencer Chang , Lisa Goodenough

The diffuse extragalactic gamma-ray background (EGRB) above 100 MeV encodes unique information about high-energy processes in the universe. Numerous sources for the EGRB have been proposed, but the two systems which are certain to make some…

Astrophysics · Physics 2009-11-07 Vasiliki Pavlidou , Brian D. Fields

Recently, the Large High-Altitude Air Shower Observatory (LHAASO) collaboration has obtained a measurement of the gamma-ray diffuse emission in the ultra-high energy range, $10-10^3$ TeV after masking the contribution of known sources. The…

High Energy Astrophysical Phenomena · Physics 2025-09-16 Vittoria Vecchiotti , Giada Peron , Elena Amato , Stefano Menchiari , Giovanni Morlino , Giulia Pagliaroli , Francesco L. Villante

We present a novel determination of the astrophysical uncertainties associated to the secondary antiproton flux originating from cosmic-ray spallation on the interstellar gas. We select a set of propagation models compatible with the recent…

High Energy Astrophysical Phenomena · Physics 2016-02-04 Carmelo Evoli , Daniele Gaggero , Dario Grasso

The origin of the diffuse gamma-ray background (DGRB), the one that remains after subtracting all individual sources from observed gamma-ray sky, is unknown. The DGRB possibly encompasses contributions from different source populations such…

High Energy Astrophysical Phenomena · Physics 2023-05-02 Saqib Hussain , Rafael Alves Batista , Elisabete M. de Gouveia Dal Pino , Klaus Dolag

As recently shown, Fermi-LAT measurements of the diffuse gamma-ray emission from the Galaxy favor the presence of a smooth softening in the primary cosmic-ray spectrum with increasing Galactocentric distance. This result can be interpreted…

High Energy Astrophysical Phenomena · Physics 2016-06-22 Daniele Gaggero , Dario Grasso , Antonio Marinelli , Alfredo Urbano , Mauro Valli

The Fermi-LAT data accumulated over 7 years of {\gamma}-ray observations, together with the high resolution gas (CO & HI) and the dust opacity maps, are used to study the emissivity of {\gamma}-rays induced by interactions of cosmic rays…

High Energy Astrophysical Phenomena · Physics 2016-06-22 Rui-zhi Yang , Felix Aharonian , Carmelo Evoli

An important contribution to the gamma-ray emission of our Galaxy is the Galactic Diffuse emission. We present specific developments within the PICARD code for modeling of Galactic cosmic ray propagation that are relevant for the…

High Energy Astrophysical Phenomena · Physics 2017-01-26 Felix Niederwanger , Olaf Reimer , Ralf Kissmann , Richard Tuffs

The presence of relativistic electrons within the diffuse gas phase of galaxy clusters is now well established, but their detailed origin remains unclear. Cosmic ray protons are also expected to accumulate during the formation of clusters…

High Energy Astrophysical Phenomena · Physics 2021-04-14 R. Adam , H. Goksu , S. Brown , L. Rudnick , C. Ferrari

Recent evidence for a large Galactic halo, based on cosmic-ray radioactive nuclei, implies a significant contribution from inverse Compton emission at high Galactic latitudes. We present predictions for the expected intensity distribution,…

Astrophysics · Physics 2007-05-23 A. W. Strong , I. V. Moskalenko , O. Reimer

Recently, the MILAGRO collaboration reported on the detection of a diffuse multi-TeV emission from a region of the Galactic disk close to the inner Galaxy. The emission is in excess of what is predicted by conventional models for cosmic ray…

Astrophysics · Physics 2015-06-30 S. Gabici , A. M. Taylor , R. J. White , S. Casanova , F. A. Aharonian

Recent studies on cosmic rays (CRs) have reported the possibility of an excess in the antiproton flux around $10-20$ GeV. However, the associated systematic uncertainties have impeded the interpretation of these findings. In this study, we…

High Energy Astrophysical Phenomena · Physics 2024-05-31 Xing-Jian Lv , Xiao-Jun Bi , Kun Fang , Peng-Fei Yin , Meng-Jie Zhao

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.…

High Energy Astrophysical Phenomena · Physics 2021-05-26 Maria Werhahn , Christoph Pfrommer , Philipp Girichidis , Georg Winner

Motivated by the PAMELA anomaly in the fluxes of cosmic-ray electron and positron, we study the cosmic gamma-ray induced by the inverse Compton (IC) scattering process in unstable dark matter scenario assuming that the anomaly is due to the…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-19 Koji Ishiwata , Shigeki Matsumoto , Takeo Moroi

Cosmic rays (CRs) are ubiquitous in the interstellar medium (ISM) of nearby galaxies, but many of their properties are not well-constrained. Gamma-ray observations provide a powerful tool in this respect, allowing us to constrain both the…

High Energy Astrophysical Phenomena · Physics 2023-07-19 Maria Werhahn , Philipp Girichidis , Christoph Pfrommer , Joseph Whittingham

High energy cosmic ray electrons and positrons, during propagation in the Galaxy, mainly lose energy through either the inverse Compton scattering (ICS) off of the interstellar radiation field (ISRF) or emitting synchrotron radiation in the…

High Energy Astrophysical Phenomena · Physics 2017-09-13 Maryam Tavakoli

Diffuse $\gamma$-ray emission is a key probe of cosmic rays (CRs) distribution within the Galaxy. However, the discrepancies between observations and theoretical model expectations highlight the need for refined uncertainty estimates. In…

High Energy Astrophysical Phenomena · Physics 2025-09-10 Xing-Jian Lv , Xiao-Jun Bi , Kun Fang , Han-Xiang Hu , Peng-Fei Yin , Meng-Jie Zhao

Recent gamma-ray observations have detected photons up to energies of a few PeV. These highly energetic gamma rays are emitted by the most powerful sources in the Galaxy. Propagating over astrophysical distances, gamma rays might interact…

High Energy Astrophysical Phenomena · Physics 2025-04-18 Gaetano Di Marco , Rafael Alves Batista , Miguel Ángel Sánchez-Conde

The Milky Way's galactic center is a highly dynamical, crowded environment. Gamma ray observations of this region, such as the excess of GeV scale gamma rays observed by Fermi LAT, have been of tremendous interest to both the high energy…

High Energy Astrophysical Phenomena · Physics 2025-09-24 Isabel S. Sands , Philip F. Hopkins , Sam B. Ponnada , Dusan Keres , Lina Necib , Yen-Hsing Julius Lin

The extragalactic background (EGB) of diffuse gamma rays can be determined by subtracting the Galactic contribution from the data. This requires a Galactic model (GM) and we include for the first time the contribution of dark matter…

Astrophysics · Physics 2009-11-13 W. de Boer , A. Nordt , C. Sander , V. Zhukov