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Various studies have implied the existence of a gaseous halo around the Galaxy extending out to 100 kpc. Galactic cosmic rays (CRs) that propagate to the halo, either by diffusion or by convection with the possibly existing large-scale…

High Energy Astrophysical Phenomena · Physics 2019-01-30 Ruo-Yu Liu , Huirong Yan , Xiang-Yu Wang , Shi Shao , Hui Li

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 present version 2 of the DRAGON code designed for computing realistic predictions of the CR densities in the Galaxy. The code numerically solves the interstellar CR transport equation (including inhomogeneous and anisotropic diffusion,…

High Energy Astrophysical Phenomena · Physics 2017-03-28 Carmelo Evoli , Daniele Gaggero , Andrea Vittino , Giuseppe Di Bernardo , Mattia Di Mauro , Arianna Ligorini , Piero Ullio , Dario Grasso

Cosmic-ray (CR) electrons and nuclei interact with the Galactic interstellar gas and produce high-energy $\gamma$ rays. The $\gamma$-ray emission rate per hydrogen atom, called emissivity, provides a unique indirect probe of the CR flux. We…

High Energy Astrophysical Phenomena · Physics 2015-06-02 Jean-Marc Casandjian

Cosmic rays travel throughout the Galaxy, leaving traces from radio to ultra-high-energy gamma rays due to interactions with the interstellar gas, radiation field and magnetic field. Therefore, it is necessary to utilize multi-wavelength…

High Energy Astrophysical Phenomena · Physics 2024-03-15 Xin-Yu He , Pei-Pei Zhang , Qiang Yuan , Yi-Qing Guo

Several observations from Fermi-LAT, up to few hundred GeV, and from H.E.S.S., up to $\sim$ 10 TeV, reported an intense $\gamma$-ray emission from the inner part of the Galactic plane. After the subtraction of point-like contributions, the…

High Energy Astrophysical Phenomena · Physics 2015-08-18 Daniele Gaggero , Dario Grasso , Antonio Marinelli , Alfredo Urbano , Mauro Valli

While supernova remnants (SNRs) are widely thought to be powerful cosmic-ray accelerators, indirect evidence comes from a small number of well-studied cases. Here we systematically determine the gamma-ray emission detected by the Fermi…

High Energy Astrophysical Phenomena · Physics 2015-07-14 F. de Palma , T. J. Brandt , J. W. Hewitt , G. Johannesson , L. Tibaldo

We present an analysis of the gamma-ray data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the direction of SNR W49B (G43.3-0.2). A bright unresolved gamma-ray source detected at a significance…

High Energy Astrophysical Phenomena · Physics 2015-05-19 LAT Collaboration

The Fermi-LAT telescope has measured the extragalactic gamma-ray background (EGB) generated by the ensemble of all extragalactic sources. The energy distribution of the EGB is well described as a power-law with a spectral index…

High Energy Astrophysical Phenomena · Physics 2020-09-09 Paolo Lipari

The diffuse gamma-ray emission between 10 and 1000 TeV from the Galactic plane was recently measured by the Large High Altitude Air Shower Observatory (LHAASO). These observations will help tremendously in constraining the propagation and…

High Energy Astrophysical Phenomena · Physics 2023-11-06 Rui Zhang , Xiaoyuan Huang , Zhi-Hui Xu , Shiping Zhao , Qiang Yuan

Recently evidence has emerged for enormous features in the gamma-ray sky observed by the Fermi-LAT instrument: bilateral `bubbles' of emission centered on the core of the Galaxy and extending to around 10 kpc above and below the Galactic…

Astrophysics of Galaxies · Physics 2011-03-24 Roland M. Crocker , Felix Aharonian

We present a systematic reassessment of 5,062 high-Galactic latitude gamma-ray sources from the Fermi-LAT 4FGL-DR4 catalog using Firmamento, a web-based platform for multi-frequency source discovery and analysis. Our goal is to provide an…

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…

High Energy Astrophysical Phenomena · Physics 2011-10-03 A. W. Strong , E. Orlando , T. R. Jaffe

Despite the growing number of gamma-ray sources detected by Fermi-LAT, about one third of the sources in each survey remains of uncertain type. We present a new deep neural network approach for the classification of unidentified or…

High Energy Astrophysical Phenomena · Physics 2021-09-28 Thorben Finke , Michael Krämer , Silvia Manconi

We propose a novel statistical method to extend Fermi-LAT catalogues of high-latitude $\gamma$-ray sources below their nominal threshold. To do so, we rely on a recent determination of the differential source-count distribution of…

High Energy Astrophysical Phenomena · Physics 2024-05-16 Aurelio Amerio , Francesca Calore , Pasquale Dario Serpico , Bryan Zaldivar

A GeV gamma-ray excess has possibly been individuated in Fermi-LAT data from the Galactic Center and interpreted in terms of Dark Matter (DM) annihilations, either in hadronic (essentially $b\bar{b}$) or leptonic channels. In order to test…

High Energy Physics - Phenomenology · Physics 2015-06-22 Marco Cirelli , Daniele Gaggero , Gaëlle Giesen , Marco Taoso , Alfredo Urbano

The Fermi-LAT data appear to have an excess of gamma rays from the inner 150 pc of the Galactic Center. The main explanations proposed for this are: an unresolved population of millisecond pulsars (MSPs), dark matter (DM) annihilation, and…

High Energy Astrophysical Phenomena · Physics 2014-03-19 Oscar Macias , Chris Gordon

The Fermi Large Area Telescope (LAT) Collaboration has recently released a catalog of 360 sources detected above 50 GeV (2FHL). This catalog was obtained using 80 months of data re-processed with Pass 8, the newest event-level analysis,…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-20 LAT Collaboration

Radio and gamma-ray emission from active galactic nuclei (AGN) are thought to share a common origin, related to the ejection phenomena in the vicinity of supermassive black holes. Thanks to its sensitivity, surveying capability, and broad…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-29 M. Giroletti , A. Reimer , L. Fuhrmann , V. Pavlidou , J. L. Richards

Spatial variations of the average properties that characterize the hadronic component of the diffuse Galactic cosmic-ray sea, in particular the spectral slope and normalization, may unveil critical information about their confinement…

High Energy Astrophysical Phenomena · Physics 2018-10-31 Mart Pothast , Daniele Gaggero , Emma Storm , Christoph Weniger