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Recent full-sky maps of the Galaxy from the Fermi Gamma-Ray Space Telescope have revealed a diffuse component of emission towards the Galactic center and extending up to roughly +/-50 degrees in latitude. This Fermi "haze" is the inverse…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Gregory Dobler , Ilias Cholis , Neal Weiner

The gamma-ray halo around Geminga is formed owing to the slow diffusion of the electrons released by the Geminga PWN. The latest HAWC and HESS observations exhibit complex features in the TeV gamma-ray spectrum of the Geminga halo. We first…

High Energy Astrophysical Phenomena · Physics 2022-05-18 Kun Fang , Xiao-Jun Bi

The HAWC Collaboration has recently reported the detection of bright and spatially extended multi-TeV gamma-ray emission from Geminga, Monogem, and a handful of other nearby, middle-aged pulsars. The angular profile of the emission observed…

High Energy Astrophysical Phenomena · Physics 2018-10-17 Dan Hooper , Tim Linden

We propose a data-driven approach to reconstruct the all-sky distribution of the dispersion measure contribution from the Galactic halo ($\mathrm{DM_{halo}}$) through a spherical harmonic expansion, enabling an investigation of its possible…

Astrophysics of Galaxies · Physics 2026-01-07 Yang Liu , Bao Wang , Puxun Wu , Jun-Jie Wei , Xue-Feng Wu

Recent studies have shown that the anisotropy is of great value to decipher cosmic rays' origin and propagation. We have built an unified scenario to describe the observations of the energy spectra and the large-scale anisotropy and called…

High Energy Astrophysical Phenomena · Physics 2024-02-29 Ai-feng Li , Qiang Yuan , Wei Liu , Yi-qing Guo

Detailed observation by the High-Altitude Water Cerenkov Observatory of the regions within about 20 pc of the nearby Geminga and PSR B0656+14 pulsars have suggested the need for the diffusion coefficient of 10-100 TeV leptons yielding the…

High Energy Astrophysical Phenomena · Physics 2018-07-20 J J Quenby

The Fermi-LAT collaboration has recently reported the detection of angular power above the photon noise level in the diffuse gamma-ray background between 1 and 50 GeV. Such signal can be used to constrain a possible contribution from…

Multiple lines of evidence indicate an anomalous injection of high-energy e+- in the Galactic halo. The recent $e^+$ fraction spectrum from the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) shows a sharp…

Astrophysics · Physics 2009-12-30 Ilias Cholis , Gregory Dobler , Douglas P. Finkbeiner , Lisa Goodenough , Neal Weiner

Cosmic rays that escape their acceleration site interact with the ambient medium and produce gamma rays as the result of inelastic proton-proton collisions. The detection of such diffuse emission may reveal the presence of an accelerator of…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Lara Nava , Stefano Gabici

LHAASO J0621$+$3755 is a TeV gamma-ray halo newly identified by LHAASO-KM2A. It is likely to be generated by electrons trapped in a slow-diffusion zone around PSR J0622$+$3749 through inverse Compton scattering. When the gamma-ray spectrum…

High Energy Astrophysical Phenomena · Physics 2021-12-01 Kun Fang , Shao-Qiang Xi , Xiao-Jun Bi

Nearby pulsars within $\sim1\,{\rm kpc}$ are considered to be possible sources of 10-500 GeV cosmic-ray positron excess measured by PAMELA and AMS-02. A TeV halo around Geminga is detected by HAWC, and the measurements of its surface…

High Energy Astrophysical Phenomena · Physics 2026-02-25 Yu Meng , Yun-Feng Liang , Ben-Yang Zhu , Xiao-Na Sun , En-Wei Liang

Recent results from the PAMELA, ATIC, PPB BETS and Fermi collaborations extend the energy range in the electron flux measurement up to unexplored energies in the hundred GeVs range confirming the bump starting at about 10GeV already…

High Energy Astrophysical Phenomena · Physics 2014-11-18 Ignacio Cernuda

Pulsars convert a significant fraction of their total spin-down power into very high-energy electrons, leading to the formation of TeV halos. It is not yet known, however, whether these sources also efficiently accelerate electrons at lower…

High Energy Astrophysical Phenomena · Physics 2024-05-14 Dan Hooper , Elena Pinetti , Anastasia Sokolenko

Recently, a few-degrees extended $\gamma$-ray halo in the direction of Geminga pulsar has been detected by HAWC, Milagro and Fermi-LAT. These observations can be interpreted with positrons ($e^+$) and electrons ($e^-$) accelerated by…

High Energy Astrophysical Phenomena · Physics 2021-12-07 Mattia Di Mauro , Silvia Manconi , Fiorenza Donato

We present a comprehensive study about the phenomenological implications of the theory describing Galactic cosmic-ray scattering onto magnetosonic and Alfv\'enic fluctuations in the $\mathrm{GeV} - \mathrm{PeV}$ domain. We compute a set of…

High Energy Astrophysical Phenomena · Physics 2021-02-17 Ottavio Fornieri , Daniele Gaggero , Silvio Sergio Cerri , Pedro De la Torre Luque , Stefano Gabici

The spatial diffusion of energetic particles in a magnetic field composed of a large-scale background and a small-scale turbulent component should be expected to be anisotropic. While such anisotropic diffusion has been known for quite a…

High Energy Astrophysical Phenomena · Physics 2025-07-17 Julien Dörner , Jonas Hellrung , Julia Becker Tjus , Horst Fichtner

Diffusive shock acceleration and diffusion propagation are essential components of the standard cosmic ray model. These theories are based on extensive observations of high-energy solar processes, providing substantial direct evidence in…

High Energy Astrophysical Phenomena · Physics 2026-05-19 Weikang Gao , Li-Zhuo Bao , Kun Fang , En-sheng Chen , Siming Liu , HongBo Hu

Decaying dark matter particles could be indirectly detected as an excess over a simple power law in the energy spectrum of the diffuse extragalactic gamma-ray background. Furthermore, since the Earth is not located at the center of the…

High Energy Physics - Phenomenology · Physics 2014-11-20 Alejandro Ibarra , David Tran , Christoph Weniger

The Tibet AS$\gamma$ collaboration has reported a diffuse $\gamma$-ray emission signal from the Galactic Plane. We consider the possibility that the diffuse emission from the outer Galactic Plane at the highest energies is produced by…

High Energy Astrophysical Phenomena · Physics 2023-01-03 G. Giacinti , T. Abounnasr , A. Neronov , D. Semikoz

It was suggested that the $\gamma$-ray halo around Geminga might not be interpreted by slow-diffusion. If the ballistic regime of electron/positron propagation is considered, the Geminga halo may be explained even with a large diffusion…

High Energy Astrophysical Phenomena · Physics 2022-09-21 Li-Zhuo Bao , Kun Fang , Xiao-Jun Bi , Sheng-Hao Wang