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The diffuse Galactic gamma-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray…

High Energy Astrophysical Phenomena · Physics 2019-08-13 T. A. Porter

Observations of diffuse Galactic gamma ray emission (DGE) by the Fermi Large Area Telescope (LAT) allow a detailed study of cosmic rays and the interstellar medium. However, diffuse emission models of the inner Galaxy underpredict the…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-03 Lin F. Yang , Joseph Silk , Alexander S. Szalay , Rosemary F. G. Wyse , Brandon Bozek , Piero Madau

Faint $\gamma$-ray signatures emerge in Fermi-LAT data stacked scaled to the characteristic $R_{500}$ radii of MCXC galaxy clusters. This third paper in a series shows a $4.3\sigma$ excess of discrete 4FGL-DR4 catalog $\gamma$-ray sources…

High Energy Astrophysical Phenomena · Physics 2025-03-14 Uri Keshet

Galaxy clusters are the largest virialised objects in the Universe, and as such, have a high dark matter (DM) concentration. This abundance of dark matter makes them promising targets for indirect DM searches. Here we report the details of…

High Energy Astrophysical Phenomena · Physics 2021-02-03 Charles Thorpe-Morgan , Denys Malyshev , Christoph-Alexander Stegen , Andrea Santangelo , Josef Jochum

Many galaxy clusters have giant halos of non-thermal radio emission, indicating the presence of relativistic electrons in the clusters. Relativistic protons may also be accelerated by merger and/or accretion shocks in galaxy clusters. These…

High Energy Astrophysical Phenomena · Physics 2018-09-19 Shao-Qiang Xi , Xiang-Yu Wang , Yun-Feng Liang , Fang-Kun Peng , Rui-Zhi Yang , Ruo-Yu Liu

We analyze publicly available Fermi-LAT high-energy gamma-ray data and confirm the existence of clear spectral feature peaked at E=130GeV. Scanning over the Galaxy we identify several disconnected regions where the observed excess…

High Energy Physics - Phenomenology · Physics 2012-10-31 Elmo Tempel , Andi Hektor , Martti Raidal

Recently, the Fermi-LAT collaboration reported upper limits on the GeV gamma-ray flux from nearby clusters of galaxies. Motivated by these limits, we study corresponding constraints on gamma-ray emissions from two specific decaying dark…

High Energy Physics - Phenomenology · Physics 2011-03-28 Jiwei Ke , Mingxing Luo , Liucheng Wang , Guohuai Zhu

Recently, some very tight constraints of annihilating dark matter have been obtained from gamma-ray data of the Milky Way and Milky Way dwarf spheroidal satellite galaxies. In this article, we report that there are two excellent galaxy…

High Energy Astrophysical Phenomena · Physics 2017-11-15 Man Ho Chan , Chung Hei Leung

Fermi-LAT observations of the Galactic Center (GC) have revealed a spherically- symmetric excess of GeV gamma rays extending to at least 10 deg from the dynamical center of the Galaxy. A critical uncertainty in extracting the intensity,…

High Energy Astrophysical Phenomena · Physics 2016-09-14 Eric Carlson , Tim Linden , Stefano Profumo

Galaxy clusters are promising targets for indirect dark matter searches. Gamma-ray signatures from the decay or annihilation of dark matter particles inside these clusters could be observable with the Fermi Large Area Telescope (LAT). Based…

High Energy Physics - Phenomenology · Physics 2015-05-30 Xiaoyuan Huang , Gilles Vertongen , Christoph Weniger

Several groups have identified an extended excess of gamma rays over the modeled foreground and background emissions towards the Galactic center (GC) based on observations with the Fermi Large Area Telescope. This excess emission is…

High Energy Physics - Phenomenology · Physics 2015-04-28 Francesca Calore , Ilias Cholis , Christopher McCabe , Christoph Weniger

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

High Energy Astrophysical Phenomena · Physics 2014-08-13 Thomas Lacroix , Celine Boehm , Joseph Silk

We show the presence of a potentially detectable gamma-ray line in the Fermi Galactic center excess in light of the secluded (vector) dark matter (DM) model in which the hidden scalar, nearly degenerate with DM in mass, mediates the…

High Energy Physics - Phenomenology · Physics 2020-08-26 Kwei-Chou Yang

Past studies have identified a spatially extended excess of $\sim$1-3 GeV gamma rays from the region surrounding the Galactic Center, consistent with the emission expected from annihilating dark matter. We revisit and scrutinize this signal…

High Energy Astrophysical Phenomena · Physics 2016-02-24 Tansu Daylan , Douglas P. Finkbeiner , Dan Hooper , Tim Linden , Stephen K. N. Portillo , Nicholas L. Rodd , Tracy R. Slatyer

Dark matter annihilations taking place in nearby subhalos could appear as gamma-ray sources without detectable counterparts at other wavelengths. In this study, we consider the collection of unassociated gamma-ray sources reported by the…

High Energy Astrophysical Phenomena · Physics 2015-12-23 Bridget Bertoni , Dan Hooper , Tim Linden

Clusters of galaxies are the largest gravitationally-bound systems in the Universe. Their dynamics are dominated by dark matter (DM), which makes them among the best targets for indirect DM searches. We analyze 12 years of data collected by…

High Energy Astrophysical Phenomena · Physics 2023-05-03 Mattia Di Mauro , Judit Pérez-Romero , Miguel A. Sánchez-Conde , Nicolao Fornengo

Using 43 months of public gamma-ray data from the Fermi Large Area Telescope, we find in regions close to the Galactic center at energies of 130 GeV a 4.6 sigma excess that is not inconsistent with a gamma-ray line from dark matter…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Christoph Weniger

Gamma ray emission from dark matter subhalos in the Milky Way has long been sought as a sign of dark matter particle annihilation. So far, searches for gamma-ray continuum from subhalos have been unsuccessful, and line searches are…

High Energy Astrophysical Phenomena · Physics 2012-07-31 Meng Su , Douglas P. Finkbeiner

The Fermi-LAT \gamma-ray data have been used to study the morphological and spectral features of the so-called GeV excess - a diffuse radiation component recently discovered towards the Galactic centre. We used the likelihood method to…

High Energy Astrophysical Phenomena · Physics 2016-04-27 Rui-zhi Yang , Felix Aharonian

Using 3.7 years of \Fermi-LAT data, we examine the diffuse 80-200 GeV emission in the inner Galaxy and find a resolved gamma-ray feature at $\sim 110-140$ GeV. We model the spatial distribution of this emission with a $\sim3\degree$ FWHM…

High Energy Astrophysical Phenomena · Physics 2012-06-15 Meng Su , Douglas P. Finkbeiner