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Here we describe an advanced multi functional, variable-energy positron beam system capable of measuring the energies of multiple positron-induced electrons in coincidence with the Doppler-shifted gamma photon resulting from the…

Gaseous outflows appear to be a universal property of type-1 and type-2 active galactic nuclei (AGN). The main diagnostic is provided by emission features shifted to higher frequency via the Doppler effect, implying that the emitting gas is…

Astrophysics of Galaxies · Physics 2022-03-18 Paola Marziani , Alice Deconto-Machado , Ascension del Olmo

We report the detection of a nearby emission-line companion to the z=4.695 quasar BR1202-0725. Deep narrow-band exposures on this field from the UH 2.2 m show a Ly alpha flux of 1.5\times\ten{-16} ergs cm^{-2} s^{-1}. High-resolution HST…

Astrophysics · Physics 2009-10-28 Esther M. Hu , Richard G. McMahon , Eiichi Egami

We demonstrate that the anomalous ionization rate observed in the Central Molecular Zone can be attributed to MeV dark matter annihilations into $e^+e^-$ pairs for galactic dark matter profiles with slopes $\gamma>1$. The low annihilation…

High Energy Physics - Phenomenology · Physics 2025-03-19 Pedro De la Torre Luque , Shyam Balaji , Joseph Silk

We compare the rise and decay timescales of $\sim$200 long-term ($\sim$weeks-months) GeV and R-band outbursts and $\sim$25 short-term ($\sim$hr-day) GeV flares in a sample of 10 blazars using light curves from the Fermi-LAT and the…

Astrophysics of Galaxies · Physics 2018-10-24 Namrata Roy , Ritaban Chatterjee , Manasvita Joshi , Aritra Ghosh

We consider the largest observed sample including all intermediate-frequency peaked (IBL) and high-frequency peaked (HBL) flaring blazars above 100 GeV up to redshift $z = 0.6$. We show that the best-fit regression line of the emitted…

High Energy Astrophysical Phenomena · Physics 2020-04-22 Giorgio Galanti , Marco Roncadelli , Alessandro De Angelis , Giovanni F. Bignami

In given article preliminary results of the research of the electron multiplication in MPGD are presented at a high level of alpha-particles background. This work has expanded borders of understanding of the streamer mode nature. It is seen…

Instrumentation and Detectors · Physics 2010-09-16 V. I. Razin , A. I. Reshetin

The final-state particles from cosmological dark matter co-annihilation are expected to equilibrate. As dictated by Hard Thermal Loop resummation, the spectrum of equilibrated quasiparticles is richer than in vacuum, with a massless gauge…

High Energy Physics - Phenomenology · Physics 2025-09-05 S. Biondini , M. Eriksson , M. Laine

The blazar zone in quasars is commonly assumed to be located inside the broad-line region at some hundreds of Schwartzschild radii from the central black hole. Now, the simultaneous Fermi/LAT and MAGIC observations of a strong flare in the…

High Energy Astrophysical Phenomena · Physics 2019-08-15 A. Stamerra , J. Becerra , G. Bonnoli , L. Maraschi , F. Tavecchio , D. Mazin , K. Saito , Y. Tanaka , D. Wood

The energy-dependence of the anisotropy (the anisotropy energy spectrum) of the large-scale diffuse gamma-ray background can reveal the presence of multiple source populations. Annihilating dark matter in the substructure of the Milky Way…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Brandon S. Hensley , Jennifer M. Siegal-Gaskins , Vasiliki Pavlidou

The two messenger results of the GeV gamma-ray excess at the Galactic center and a probable antiproton excess in the recent AMS-02 observation suggest that these two anomalies may be owing to the same origin --- the dark matter (DM)…

High Energy Physics - Phenomenology · Physics 2017-09-20 Lian-Bao Jia

It is commonly believed that blazar jets are relativistic magnetized plasma outflows from supermassive black holes. One key question is how the jets dissipate magnetic energy to accelerate particles and drive powerful multi-wavelength…

High Energy Astrophysical Phenomena · Physics 2022-01-26 Haocheng Zhang , Xiaocan Li , Dimitrios Giannios , Fan Guo , Hannes Thiersen , Markus Böttcher , Tiffany Lewis , Tonia Venters

Relativistic jets in AGN in general, and in blazars in particular, are the most energetic and among the most powerful astrophysical objects known so far. Their relativistic nature provides them with the ability to emit profusely at all…

High Energy Astrophysical Phenomena · Physics 2012-10-09 Ivan Agudo , Alan P. Marscher , Svetlana G. Jorstad , Jose L. Gomez

We present a new time-dependent inhomogeneous jet model of non-thermal blazar emission, which reproduces the entire spectral energy distribution together with the rapid gamma-ray variability. Ultra-relativistic leptons are injected at the…

Astrophysics · Physics 2011-02-11 Timothé Boutelier , Gilles Henri , Pierre-Olivier Petrucci

Multiwavelength (MWL) observations of the blazar PKS 2155-304 during two weeks in July and August 2006, the period when two exceptional flares at very high energies (VHE, E>= 100 GeV) occurred, provide a detailed picture of the evolution of…

High Energy Astrophysical Phenomena · Physics 2015-06-03 HESS Collaboration , A. Abramowski , F. Acero , F. Aharonian , A. G. Akhperjanian , G. Anton , A. Balzer , A. Barnacka , U. Barres de Almeida , Y. Becherini , J. Becker , B. Behera , W. Benbow , K. Bernlöhr , A. Bochow , C. Boisson , J. Bolmont , P. Bordas , T. Boutelier , J. Brucker , F. Brun , P. Brun , T. Bulik , I. Büsching , S. Carrigan , S. Casanova , M. Cerruti , P. M. Chadwick , A. Charbonnier , R. C. G. Chaves , A. Cheesebrough , L. -M. Chounet , A. C. Clapson , G. Coignet , G. Cologna , P. Colom , J. Conrad , N. Coudreau , M. Dalton , M. K. Daniel , I. D. Davids , B. Degrange , C. Deil , H. J. Dickinson , A. Djannati-Ataï , W. Domainko , L. O'C. Drury , F. Dubois , G. Dubus , K. Dutson , J. Dyks , M. Dyrda , P. Edwards , K. Egberts , P. Eger , P. Espigat , L. Fallon , C. Farnier , S. Fegan , F. Feinstein , M. V. Fernandes , A. Fiasson , G. Fontaine , A. Förster , M. Füßling , Y. A. Gallant , H. Gast , M. J. Gaylard , L. Gérard , D. Gerbig , B. Giebels , J. F. Glicenstein , B. Glück , P. Goret , D. Göring , S. Häffner , J. D. Hague , D. Hampf , M. Hauser , S. Heinz , G. Heinzelmann , G. Henri , G. Hermann , J. A. Hinton , A. Hoffmann , W. Hofmann , P. Hofverberg , M. Holler , D. Horns , A. Jacholkowska , O. C. de Jager , C. Jahn , M. Jamrozy , I. Jung , M. A. Kastendieck , K. Katarzyński , U. Katz , S. Kaufmann , D. Keogh , D. Khangulyan , B. Khélifi , M. Klein , D. Klochkov , W. Kluźniak , T. Kneiske , Nu. Komin , K. Kosack , R. Kossakowski , P. Kubanek , H. Laffon , G. Lamanna , D. Lennarz , J. -P. Lenain , T. Lohse , A. Lopatin , C. -C. Lu , V. Marandon , A. Marcowith , J. M. Martin , J. Masbou , D. Maurin , N. Maxted , T. J. L. McComb , M. C. Medina , J. Méhault , G. Melady , N. Nguyen , R. Moderski , B. Monard , E. Moulin , C. L. Naumann , M. Naumann-Godo , M. de Naurois , D. Nedbal , D. Nekrassov , B. Nicholas , J. Niemiec , S. J. Nolan , S. Ohm , E. de Oña Wilhelmi , B. Opitz , M. Ostrowski , I. Oya , M. Panter , M. Paz Arribas , G. Pedaletti , G. Pelletier , P. -O. Petrucci , S. Pita , G. Pühlhofer , M. Punch , A. Quirrenbach , M. Raue , S. M. Rayner , A. Reimer , O. Reimer , M. Renaud , R. de los Reyes , F. Rieger , J. Ripken , L. Rob , S. Rosier-Lees , G. Rowell , B. Rudak , C. B. Rulten , J. Ruppel , F. Ryde , V. Sahakian , A. Santangelo , R. Schlickeiser , F. M. Schöck , A. Schulz , U. Schwanke , S. Schwarzburg , S. Schwemmer , M. Sikora , J. L. Skilton , H. Sol , G. Spengler , Ł. Stawarz , R. Steenkamp , C. Stegmann , F. Stinzing , K. Stycz , I. Sushch , A. Szostek , J. -P. Tavernet , R. Terrier , M. Tluczykont , A. Tzioumis , K. Valerius , C. van Eldik , G. Vasileiadis , C. Venter , L. Venter , J. P. Vialle , A. Viana , P. Vincent , H. J. Völk , F. Volpe , S. Vorobiov , M. Vorster , S. J. Wagner , M. Ward , R. White , A. Wierzcholska , M. Zacharias , A. Zajczyk , A. A. Zdziarski , A. Zech , H. -S. Zechlin

In this work we perform an analysis of the recent AMS-02 antiproton flux and the antiproton-to-proton ratio in the framework of simplified dark matter models. To predict the AMS-02 observables we adopt the propagation and injection…

High Energy Physics - Phenomenology · Physics 2017-05-24 Tong Li

The X-ray, Ultraviolet, Optical emission from radio-quiet AGNs, black hole binaries, and other compact sources, in general, follow a lognormal flux distribution, a linear rms-flux relation, and a (broken) power-law power spectral densities…

High Energy Astrophysical Phenomena · Physics 2020-03-04 Pankaj Kushwaha , Atreyee Sinha , Ranjeev Misra , K. P. Singh , E. M. de Gouveia Dal Pino

Context. Blazars are a subset of active galactic nuclei (AGN) with jets that are oriented along our line of sight. Variability and spectral energy distribution (SED) studies are crucial tools for understanding the physical processes…

We consider a Compton cloud (CC) surrounding a black hole (BH) in an accreting black hole system, where electrons propagate with thermal and bulk velocities.In that cloud, soft (disk) photons may be upscattered off these energetic electrons…

High Energy Astrophysical Phenomena · Physics 2018-06-13 Philippe Laurent , Lev Titarchuk

The AMS-02 collaboration has just released its first result of the cosmic positron fraction $e^+/(e^-+e^+)$ with high precision up to $\sim 350$ GeV. The AMS-02 result shows the same trend with the previous PAMELA result, which requires…

High Energy Astrophysical Phenomena · Physics 2014-07-15 Qiang Yuan , Xiao-Jun Bi , Guo-Ming Chen , Yi-Qing Guo , Su-Jie Lin , Xinmin Zhang