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We investigate the extent to which the uncertainties associated with the propagation of Galactic cosmic rays impact upon estimates for the gamma-ray flux from the mid-latitude region. We consider contributions from both standard…

High Energy Astrophysical Phenomena · Physics 2010-11-18 Daniel T. Cumberbatch , Yue-Lin Sming Tsai , Leszek Roszkowski

Gamma-ray emission produced by interactions between cosmic rays (CRs) and interstellar gas traces the product of their densities throughout the Milky Way. The outer Galaxy is a privileged target of investigation to separate interstellar…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Luigi Tibaldo , Isabelle A. Grenier , Tsunefumi Mizuno

Very high energy (VHE, energy $E \gtrsim 100$\,GeV) \gamma-rays from cosmological sources are attenuated due to the interaction with photons of the extragalactic background light (EBL) in the ultraviolet to infrared wavelength band. The…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-05 Manuel Meyer , Martin Raue , Daniel Mazin , Dieter Horns

Using a significantly enlarged \textit{Fermi}-LAT BL Lac objects (BL Lacs) sample, we construct the gamma-ray luminosity function (GLF) of BL Lacs, by the joint use of the space density distribution and source counts distribution. We use…

High Energy Astrophysical Phenomena · Physics 2019-10-02 Yankun Qu , Houdun Zeng , Dahai Yan

We reconstruct the extra-galactic gamma-ray source-count distribution, or $dN/dS$, of resolved and unresolved sources by adopting machine learning techniques. Specifically, we train a convolutional neural network on synthetic 2-dimensional…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-16 Aurelio Amerio , Alessandro Cuoco , Nicolao Fornengo

Fast radio bursts (FRBs) are one of the most exciting new mysteries of astrophysics. Their origin is still unknown, but recent observations seem to link them to soft gamma repeaters and, in particular, to magnetar giant flares (MGFs). The…

High Energy Astrophysical Phenomena · Physics 2023-01-18 Giacomo Principe , Niccolò Di Lalla , Leonardo Di Venere , Michela Negro , Francesco Longo

The Large Area Telescope (LAT) on-board the Fermi satellite detected emission above 20 MeV only in a small fraction of the long gamma-ray bursts (GRBs) detected by the Fermi Gamma-ray Burst Monitor (GBM) at 8 keV-40 MeV. Those bursts that…

High Energy Astrophysical Phenomena · Physics 2013-03-08 Dafne Guetta

We present a likelihood profile stacking technique based on the {\it Fermi}-Large Area Telescope (LAT) data to explore the $\gamma$-ray characteristics of {\it Fermi}-LAT undetected astrophysical populations. The pipeline is applied to a…

High Energy Astrophysical Phenomena · Physics 2019-09-10 Vaidehi S. Paliya , Alberto Dominguez , Marco Ajello , Anna Franckowiak , Dieter Hartmann

Recent ROSAT surveys suggest that galaxies constitute the new class of X-ray sources required to explain the full phenomenology of the cosmic X-Ray Background (XRB). To test this hypothesis, we compute the two-point cross-correlation…

Astrophysics · Physics 2016-08-30 A. Refregier , D. J. Helfand , R. G. McMahon

We model the possible afterglow of the Fermi GBM event associated with LIGO detection GW150914, under the assumption that the gamma-ray are produced by a short GRB-like relativistic outflow. We model GW150914-GBM as both a weak, on-axis…

High Energy Astrophysical Phenomena · Physics 2016-07-13 Brian J. Morsony , Jared C. Workman , Dominic M. Ryan

We update the list of GeV-TeV extragalactic \gamma-ray sources using the 2-year catalog from the Fermi-LAT and recent results ground-based \gamma-ray telescopes. Breaks in the spectra between the high energy (100 MeV <E< 300 GeV) and the…

High Energy Astrophysical Phenomena · Physics 2013-06-05 D. A. Sanchez , S. Fegan , B. Giebels

Large-scale fluctuations of the X-ray background are investigated using the ROSAT All-Sky Survey. The autocorrelation function of the extragalactic background at 1 keV is determined at separations 0.1 - 40 deg. We detect a significant…

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

We report the identification of a positive cross-correlation signal between the unresolved $\gamma$-ray emission, measured by the \emph{Fermi} Large Area Telescope, and four different galaxy cluster catalogues. The selected catalogues peak…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-07 Manuel Colavincenzo , Xiuhui Tan , Simone Ammazzalorso , Stefano Camera , Marco Regis , Jun-Qing Xia , Nicolao Fornengo

We present a systematic search for spatial association between a high confidence sample of 3,166 morphologically selected galaxy mergers drawn from the initial convolutional neural network (CNN) catalog of 328,151 candidate mergers and…

High Energy Astrophysical Phenomena · Physics 2025-09-15 Siddhant Manna , Shantanu Desai

Measuring the diffuse Galactic gamma-ray flux in the TeV range is difficult for ground-based gamma-ray telescopes because of the residual cosmic-ray background, which is higher than the gamma-ray flux by several orders of magnitude. Its…

High Energy Astrophysical Phenomena · Physics 2020-01-22 A. Neronov , D. V. Semikoz

BL Lac objects are an extreme type of active galactic nuclei (AGNs) that belong to the largest population of $\gamma$-ray sources: blazars. This class of AGNs shows a double-bumped spectral energy distribution that is commonly described in…

High Energy Astrophysical Phenomena · Physics 2020-04-08 E. J. Marchesini , A. Paggi , F. Massaro , N. Masetti , R. D'Abrusco , I. Andruchow , R. de Menezes

The all-sky survey in high-energy gamma rays (E$>$30 MeV) carried out by the Energetic Gamma Ray Experiment Telescope (EGRET) aboard the Compton Gamma-Ray Observatory provides a unique opportunity to examine in detail the diffuse gamma-ray…

Astrophysics · Physics 2011-05-05 P. Sreekumar

The Ep,i - Eiso correlation is one of the most intriguing properties of GRBs, with significant implications for the understanding of the physics and geometry of the prompt emission, the identification and investigation of different classes…

High Energy Astrophysical Phenomena · Physics 2010-02-12 L. Amati

We present a model for estimating the blazar contribution to the extragalactic gamma-ray background (EGRB) in the EGRET energy range. It is based on inverse-Compton scattering as the dominant gamma-ray production process in the jets of flat…

Astrophysics · Physics 2007-05-23 A. Muecke , M. Pohl
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