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The physical origin of the >0.1 GeV emission detected from Gamma-Ray Bursts (GRBs) by the Fermi satellite has not yet been completely understood. In this work we consider the GeV light curves of ten GRBs with measured redshift detected by…

High Energy Astrophysical Phenomena · Physics 2015-06-22 L. Nava , G. Vianello , N. Omodei , G. Ghisellini , G. Ghirlanda , A. Celotti , F. Longo , R. Desiante , R. Barniol Duran

We report a Fermi-LAT $\gamma$-ray analysis for the Chamaeleon molecular-cloud complex using a total column density (NH) model based on the dust optical depth at 353 GHz ($\tau_{353}$) with the Planck thermal dust emission model. Gamma rays…

Recent direct measurements of Galactic cosmic ray spectra by balloon/space-borne detectors reveal spectral hardenings of all major nucleus species at rigidities of a few hundred GV. The all-sky diffuse gamma-ray emissions measured by the…

High Energy Astrophysical Phenomena · Physics 2018-03-21 Yi-Qing Guo , Qiang Yuan

A fundamental problem of cosmic ray (CR) physics is the determination of the average properties of Galactic CRs outside the Solar system. Starting from COS-B data in the 1980's, gamma-ray observations of molecular clouds in the Gould Belt…

High Energy Astrophysical Phenomena · Physics 2015-06-05 M. Kachelriess , S. Ostapchenko

An excess of gamma rays at GeV energies has been detected in the Fermi-LAT data. This signal comes from a narrow region around the Galactic Center and has been interpreted as possible evidence for light (30 GeV) dark matter particles.…

High Energy Astrophysical Phenomena · Physics 2015-01-30 Thomas Lacroix

We search for gamma-ray emission from 114 Galactic high mass X-ray binaries, including 4 well studied catalogued sources, in 12.5 years of Fermi-LAT data in conjunction with the 10-year point source catalogue. Where a gamma-ray excess…

High Energy Astrophysical Phenomena · Physics 2022-03-02 Max Harvey , Cameron B. Rulten , Paula M. Chadwick

We report evidence for extended gamma-ray emission from the Virgo, Fornax and Coma clusters based on a maximum-likelihood analysis of the 3-year Fermi-LAT data. For all three clusters, excess emission is observed within three degrees of the…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Jiaxin Han , Carlos S. Frenk , Vincent R. Eke , Liang Gao , Simon D. M. White

For more than a decade now the complete origin of the diffuse gamma-ray emission background (EGRB) has been unknown. Major components like unresolved star-forming galaxies (making <50% of the EGRB) and blazars (<23%), have failed to explain…

High Energy Astrophysical Phenomena · Physics 2014-04-10 Aleksandra Dobardzic , Tijana Prodanovic

The diffuse Galactic gamma-ray data from the region of the Galactic Center has been collected by the LAT instrument on the Fermi Gamma-Ray Space Telescope. In this paper we argue that it may be able to provide an unambiguous evidence of…

High Energy Astrophysical Phenomena · Physics 2009-09-09 Leszek Roszkowski , Yue-Lin Sming Tsai

Observations of high energy gamma rays recently revealed a persistent source in spatial coincidence with the binary system Eta Carinae. Since modulation of the observed gamma-ray flux on orbital time scales has not been reported so far, an…

High Energy Astrophysical Phenomena · Physics 2012-08-14 K. Reitberger , O. Reimer , A. Reimer , M. Werner , K. Egberts , H. Takahashi

Our Galaxy resides in the center of a vast "Halo" of Dark Matter (DM). This concentration produces, in many viable particle physics models, an indirect Weakly Interacting Massive Particle (WIMP) annihilation signal that peaks in the…

High Energy Physics - Phenomenology · Physics 2015-03-17 Brandon Anderson

The Cygnus Loop is a nearby supernova remnant (SNR) observed across the electromagnetic spectrum. With the analysis of 6 years of Fermi/LAT data we find that, what previous studies had considered a single source, consists of an extended…

High Energy Astrophysical Phenomena · Physics 2015-03-04 I. Reichardt , R. Terrier , J. West , S. Safi-Harb , E. de Oña-Wilhelmi , J. Rico

The global contribution of unresolved gamma-ray point sources to the extragalactic gamma-ray background has been recently measured down to gamma-ray fluxes lower than those reached with standard source detection techniques, and by employing…

High Energy Astrophysical Phenomena · Physics 2020-05-27 Silvia Manconi , Michael Korsmeier , Fiorenza Donato , Nicolao Fornengo , Marco Regis , Hannes Zechlin

Models of quantum gravity suggest that the vacuum should be regarded as a medium with quantum structure that may have non-trivial effects on photon propagation, including the violation of Lorentz invariance. Fermi Large Area Telescope (LAT)…

High Energy Astrophysical Phenomena · Physics 2019-04-24 John Ellis , Rostislav Konoplich , Nikolaos E. Mavromatos , Linh Nguyen , Alexander S. Sakharov , Edward K. Sarkisyan-Grinbaum

In this paper we report the Fermi Large Area Telescope (LAT) detection of the gamma-ray emission toward the young star forming region W43. Using the latest source catalog and diffuse background models, the extended gamma-ray excess is…

High Energy Astrophysical Phenomena · Physics 2020-08-19 Rui-zhi Yang , Yuan Wang

The Fermi Large Area Telescope (LAT) has provided the most detailed view to date of the emission towards the Galactic centre (GC) in high-energy gamma-rays. This paper describes the analysis of data taken during the first 62 months of the…

High Energy Astrophysical Phenomena · Physics 2017-02-22 LAT Collaboration

Fermi LAT (Large Area Telescope) and GBM (Gamma ray Burst Monitor) observations of GRBs are briefly reviewed, keeping in mind EGRET expectations. Using gamma\gamma constraints on outflow Lorentz factors, leptonic models are pitted against…

High Energy Astrophysical Phenomena · Physics 2015-05-19 Charles D. Dermer

We report the discovery of extended gamma-ray emission measured by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the region of the supernova remnant (SNR) HB3 (G132.7+1.3) and the W3 HII complex adjacent to…

High Energy Astrophysical Phenomena · Physics 2016-02-17 H. Katagiri , K. Yoshida , J. Ballet , M. H. Grondin , Y. Hanabata , J. W. Hewitt , H. Kubo , M. Lemoine-Goumard

We use the recent measurement of the isotropic $\gamma$-ray background (IGRB) by Fermi LAT and analysis of the contribution of unresolved point $\gamma$-ray sources to IGRB to build constraints on the models of ultra-high cosmic rays…

High Energy Astrophysical Phenomena · Physics 2016-11-23 Oleg Kalashev