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We present the first interpretation of the new isotropic diffuse gamma-ray background (IGRB), measured by the Fermi Large Area Telescope (LAT), based on a statistical analysis. We demonstrate that the gamma-ray emission from unresolved…

High Energy Astrophysical Phenomena · Physics 2015-02-11 Mattia Di Mauro

Electron-positron annihilation line from a Galactic center direction was discovered by the balloon-borne germanium gamma-ray telescope, and confirmed by OSSE experiment of CGRO mission. Extensive observations by INTEGRAL observatory permit…

High Energy Astrophysical Phenomena · Physics 2016-12-08 G. S. Bisnovatyi-Kogan , A. S. Pozanenko

The energy spectra of TeV gamma-rays from blazars, after being corrected for intergalatic absorption in the Extragalactic Background Light (EBL), appear unusually hard, a fact that poses challenges to the conventional models of particle…

Astrophysics · Physics 2009-11-13 F. Aharonian , D. Khangulyan , L. Costamante

We combine a semi-analytic galaxy formation model (Nulsen and Fabian 1997) with a prescription for the obscured growth of massive black holes (Nulsen and Fabian 2000; Fabian 1999), to reproduce the hard X-ray background (XRB), the local…

Astrophysics · Physics 2009-09-17 R. J. Wilman , A. C. Fabian , P. E. J. Nulsen

Deep X-ray surveys have shown that the cosmic X-ray background (XRB) is largely due to the accretion onto supermassive black holes, integrated over the cosmic time. These surveys have resolved more than 80% of the 0.1-10 keV X-ray…

Astrophysics · Physics 2009-11-10 G. Hasinger

We use 15 years of $\gamma$-ray data from INTEGRAL/SPI in a refined investigation of the morphology of the Galactic bulge positron annihilation signal. Our spatial analysis confirms that the signal traces the old stellar population in the…

High Energy Astrophysical Phenomena · Physics 2021-10-20 Thomas Siegert , Roland M. Crocker , Oscar Macias , Fiona H. Panther , Francesca Calore , Deheng Song , Shunsaku Horiuchi

The public data from the EGRET space telescope on diffuse galactic gamma rays in the energy range from 0.1 to 10 GeV show an excess for energies above 1 GeV in comparison with the expectations from conventional galactic models. This excess…

High Energy Physics - Phenomenology · Physics 2007-05-23 W. de Boer

We make a detailed analysis of the indirect diffuse gamma-ray signals from dark matter annihilation in the Galaxy. We include the prompt emission, as well as the emission from inverse Compton scattering whenever the annihilation products…

High Energy Astrophysical Phenomena · Physics 2012-11-14 Steve Blanchet , Julien Lavalle

The extragalactic background is composed of the emission from all astrophysical sources, both resolved and unresolved, in addition to any diffuse components. In the last decade, there has been significant progress in our understanding of…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-23 Jonathan Biteau

Recent preliminary results from the PAMELA experiment indicate the presence of an excess of cosmic ray positrons above 10 GeV. In this letter, we consider possibility that this signal is the result of dark matter annihilations taking place…

High Energy Physics - Phenomenology · Physics 2009-12-30 Ilias Cholis , Lisa Goodenough , Dan Hooper , Melanie Simet , Neal Weiner

We present the energy spectra of the fluxes of positrons, anti-protons and photons generated by Dark Matter annihilations in our galaxy, as univocally predicted by the model of Minimal Dark Matter. Due to multi-TeV masses and to the…

High Energy Physics - Phenomenology · Physics 2008-11-26 Marco Cirelli , Roberto Franceschini , Alessandro Strumia

The Universe is filled with a diffuse background of MeV gamma-rays and PeV neutrinos, whose origins are unknown. Here, we propose a scenario that can account for both backgrounds simultaneously. Low-luminosity active galactic nuclei have…

High Energy Astrophysical Phenomena · Physics 2021-09-28 Shigeo S. Kimura , Kohta Murase , Peter Mészáros

We present results of a study of the Galactic hard X-ray and soft gamma-ray background emission performed with the IBIS telescope aboard the INTEGRAL observatory using data obtained over more than 20 years of operations. The study of the…

High Energy Astrophysical Phenomena · Physics 2024-12-30 Roman Krivonos , Ekaterina Shtykovskaya , Sergey Sazonov

Over the past few decades, an anomalous 511 keV gamma-ray line has been observed from the centre of the Milky Way. Dark matter (DM) in the form of light weakly interacting massive particles (WIMPs) annihilating into electron-positron pairs…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-01 Ryan J. Wilkinson , Aaron C. Vincent , Celine Boehm , Christopher McCabe

"Diffuse" gamma rays consist of several components: truly diffuse emission from the interstellar medium, the extragalactic background, whose origin is not firmly established yet, and the contribution from unresolved and faint Galactic point…

Astrophysics · Physics 2015-06-24 I. V. Moskalenko , A. W. Strong , O. Reimer

We propose a novel framework where MeV-scale Dirac Dark Matter annihilates into axion-like particles, providing a natural explanation for the 511 keV gamma-ray line observed in the Galactic Center. The relic abundance is determined by…

High Energy Physics - Phenomenology · Physics 2026-03-19 Mohammad Aghaie , Pedro De la Torre Luque , Alessandro Dondarini , Daniele Gaggero , Giulio Marino , Paolo Panci

Deep X-ray surveys have shown that the cosmic X-ray background (XRB) is largely due to the accretion onto supermassive black holes, integrated over cosmic time. The ROSAT, Chandra and XMM-Newton satellites have resolved more than 80% of the…

Astrophysics · Physics 2007-05-23 Guenther Hasinger

About one year ago, it was speculated that decaying or annihilating Light Dark Matter (LDM) particles could explain the flux and extension of the 511 keV line emission in the galactic centre. Here we present a thorough comparison between…

Astrophysics · Physics 2009-11-11 Y. Ascasibar , P. Jean , C. Boehm , J. Knoedlseder

Shadow observations provide a powerful tool to separate foreground components of the soft diffuse X-ray background (SDXB) from the background components. Such observations have now established that the ``local'' foreground is made of the…

Astrophysics of Galaxies · Physics 2025-07-18 Anjali Gupta , Smita Mathur , Joshua Kingsbury , Esma Korkmaz , Sanskriti Das , Yair Krongold , Manami Roy , Armando Lara-DI

The Fermi Large Area Telescope observed an excess in gamma ray emission spectrum coming from the center of the Milky Way galaxy. This data reveals that a light Dark Matter (DM) candidate of mass in the range 31-40 GeV, dominantly decaying…

High Energy Physics - Phenomenology · Physics 2015-06-19 Dilip Kumar Ghosh , Subhadeep Mondal , Ipsita Saha