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We investigate the effects of unparticles on gamma gamma--> gamma gamma scattering for photon collider mode of the future multi-TeV e^+e^- linear collider. We show the effects of unparticles on the differential, and total scattering cross…

High Energy Physics - Phenomenology · Physics 2008-11-26 O. Cakir , K. O. Ozansoy

Three different methods of measuring cosmology with gamma-ray bursts (GRBs) have been proposed since a relation between the $\gamma$-ray energy $E_{\gamma} $ of a GRB jet and the peak energy $E_p$ of the $\nu F_{\nu}$ spectrum in the burst…

Astrophysics · Physics 2009-11-10 D. Xu , Z. G. Dai , E. W. Liang

The observation in the GeV band of distant blazars has been recently used to put constraints on the Extragalactic Background Light (EBL) and Extragalactic Magnetic Fields (EGMF). To support such claims one has to assume that the leptonic…

High Energy Astrophysical Phenomena · Physics 2013-11-27 Andrey Saveliev , Carmelo Evoli , Guenter Sigl

Context. Explaining the accelerated expansion of the Universe is one of the fundamental challenges in physics today. Cosmography provides information about the evolution of the universe derived from measured distances, assuming only that…

Cosmology and Nongalactic Astrophysics · Physics 2016-10-05 Marek Demianski , Ester Piedipalumbo , Disha Sawant , Lorenzo Amati

Ongoing MeV telescopes such as INTEGRAL/SPI and Fermi/GBM, and proposed telescopes including the recently accepted COSI and the e-ASTROGAM and AMEGO missions, provide another window in understanding transients. Their signals contain…

High Energy Astrophysical Phenomena · Physics 2023-03-13 Shing-Chi Leung

In Paper I we present a new model for the Galactic distribution of free electrons. In this paper we describe the input data and methodology for determining the structure and parameters of the model. Tables of the input data are provided and…

Astrophysics · Physics 2007-05-23 J. M. Cordes , T. J. W. Lazio

We explore the potential of an artificial neural network (ANN) based method intelligence to probe the propagation of cosmic $\gamma$-ray photons in the extragalactic Universe. The journey of $\gamma$-rays emitted from a distant source like…

High Energy Astrophysical Phenomena · Physics 2021-09-29 K K Singh , V K Dhar , P J Meintjes

The version 3.01 of ELMAG, a Monte Carlo program for the simulation of electromagnetic cascades initiated by high-energy photons and electrons interacting with extragalactic background light (EBL), is presented. Pair production and inverse…

High Energy Astrophysical Phenomena · Physics 2020-05-20 M. Blytt , M. Kachelriess , S. Ostapchenko

We motivate the use of differentiable probabilistic programming techniques in order to account for the large model-space inherent to astrophysical $\gamma$-ray analyses. Targeting the longstanding Galactic Center $\gamma$-ray Excess (GCE)…

High Energy Astrophysical Phenomena · Physics 2026-04-13 Siddharth Mishra-Sharma , Tracy R. Slatyer , Yitian Sun , Yuqing Wu

The desire to extend the Hubble Diagram to higher redshifts than the range of current Type Ia Supernovae observations has prompted investigation into spectral correlations in Gamma Ray Bursts, in the hope that standard candle-like…

Astrophysics · Physics 2009-11-11 Fiona C. Speirits , Martin A. Hendry , Alejandro Gonzalez

The unexpectedly hard very-high-energy (VHE; $E > 100$ GeV) $\gamma$-ray spectra of a few distant blazars have been interpreted as evidence for a reduction of the $\gamma\gamma$ opacity of the Universe due to the interaction of VHE…

High Energy Astrophysical Phenomena · Physics 2017-02-08 Hassan Abdalla , Markus Boettcher

It is believed that the observed diffuse gamma ray emission from the galactic plane is the result of interactions between cosmic rays and the interstellar gas. Such emission can be amplified if cosmic rays penetrate into dense molecular…

Astrophysics · Physics 2008-11-26 Stefano Gabici , Felix Aharonian , Pasquale Blasi

Gamma-ray emission from large structures is useful for tracing the propagation and distribution of cosmic rays throughout our Galaxy. For example, the search for gamma-ray emission from Giant Molecular Clouds may allow us to probe the flux…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Henrike Fleischhack , Hugo Alberto Ayala Solares , Petra Huentemeyer , Matthew Coel

We study the high latitude (|b|>10) diffuse gamma-ray emission in the Galaxy in light of the recently published data from the Fermi collaboration at energies between 100 MeV and 100 GeV. The unprecedented accuracy in these measurements…

High Energy Astrophysical Phenomena · Physics 2013-04-16 I. Cholis , M. Tavakoli , C. Evoli , L. Maccione , P. Ullio

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

In order to test the efficacy of Gamma-ray Bursts (GRB) as cosmological probes, we characterize the scatter in the correlations between six pairs of GRB observables, which have previously also been studied in arXiv:2011.14040. However, some…

High Energy Astrophysical Phenomena · Physics 2024-10-28 Sarveshkumar Purohit , Shantanu Desai

We present the BACCO project, a simulation framework specially designed to provide highly-accurate predictions for the distribution of mass, galaxies, and gas as a function of cosmological parameters. In this paper, we describe our main…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-04 Raul E. Angulo , Matteo Zennaro , Sergio Contreras , Giovanni Aricò , Marcos Pellejero-Ibañez , Jens Stücker

The presence of weak intergalactic magnetic fields can be studied by their effect on electro-magnetic cascades induced by multi-TeV gamma-rays in the cosmic radiation background. Small deflections of secondary electrons and positrons as the…

High Energy Astrophysical Phenomena · Physics 2013-05-29 Markus Ahlers

Cosmic-ray background fluxes were modeled based on existing measurements and theories and are presented here. The model, originally developed for the Gamma-ray Large Area Space Telescope (GLAST) Balloon Experiment, covers the entire solid…

Astrophysics · Physics 2009-11-10 T. Mizuno , T. Kamae , G. Godfrey , T. Handa , D. J. Thompson , D. Lauben , Y. Fukazawa , M. Ozaki

The spectrum of cosmic-ray electrons depends sensitively on the history and spatial distribution of nearby sources. Given our limited observational handle on cosmic-ray sources, any model remains necessarily probabilistic. Previously,…

High Energy Astrophysical Phenomena · Physics 2025-08-08 Nikolas Frediani , Michael Krämer , Philipp Mertsch , Kathrin Nippel
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