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In measurements of in-room radio channel responses an avalanche effect can be observed: earliest signal components, which appear well separated in delay, are followed by an avalanche of components arriving with increasing rate of…

Mathematical Physics · Physics 2015-05-28 Troels Pedersen , Gerhard Steinböck , Bernard H. Fleury

Several studies have confirmed visible light and ultraviolet emission during water molecule radiolysis.However radiofrequency (RF) emissions have been scarcely investigated.This simulation study has revealed that the gamma radiolysis of…

Applied Physics · Physics 2023-03-22 K A Pradeep Kumar , G A Shanmugha Sundaram , S Venkatesh , R Thiruvengadathan

We searched for the emission of microwave radiation in the Ku band generated by a 95 keV electron beam in air. We unequivocally detected the radiation, and measured its yield and angular dependence. Both the emitted power and its angular…

High Energy Astrophysical Phenomena · Physics 2014-10-20 E. Conti , G. Collazuol , G. Sartori

The degree of beaming in Gamma-Ray Bursts (GRBs) is currently unknown. The uncertainty in the gamma-ray beaming angle, theta, leaves the total energy release (proportional to theta^2) and the event rate per galaxy (proportional to…

Astrophysics · Physics 2009-10-31 Rosalba Perna , Abraham Loeb

Electromagnetic ion cyclotron waves are expected to pitch-angle scatter and cause atmospheric precipitation of relativistic ($> 1$ MeV) electrons under typical conditions in Earth's radiation belts. However, it has been a longstanding…

Large-scale diffuse radio emission is observed in some clusters of galaxies. There is ample of evidence that the emission has its origin in synchrotron losses of relativistic electrons, accelerated in the course of clusters mergers. In a…

Astrophysics · Physics 2009-11-13 M. Hoeft , M. Brueggen , G. Yepes , S. Gottloeber , A. Schwope

In recent years, radio detection of ultra-high-energy cosmic rays (UHECRs), with energies above $10^{18}$ eV, has become an established technique. The radio emissions can be simulated with high accuracy using Monte Carlo codes such as…

Instrumentation and Methods for Astrophysics · Physics 2026-05-01 Arsène Ferrière

The current detectors of gamma-ray emission specially at TeV energies have too poor resolution to determine whether this emission is produced in the jet or in the core, particularly of low luminous, non-blazar AGNs (like radio galaxies). In…

High Energy Astrophysical Phenomena · Physics 2016-10-28 Behrouz Khiali , Elisabete M. de Gouveia Dal Pino , Hélène Sol

The overwhelming foreground contamination is one of the primary impediments to probing the Epoch of Reionization (EoR) through measuring the redshifted 21 cm signal. Among various foreground components, radio halos are less studied and…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-17 Weitian Li , Haiguang Xu , Zhixian Ma , Dan Hu , Zhenghao Zhu , Chenxi Shan , Jingying Wang , Junhua Gu , Dongchao Zheng , Xiaoli Lian , Qian Zheng , Yu Wang , Jie Zhu , Xiang-Ping Wu

Context. The recent discovery of so-called mega radio halos as a new class of diffuse, steep-spectrum radio sources in clusters of galaxies has raised questions about the origin and the evolution of cluster-wide radio emission. Aims. We…

High Energy Astrophysical Phenomena · Physics 2024-10-02 Luca Beduzzi , Franco Vazza , Virginia Cuciti , Gianfranco Brunetti , Marcus Brüggen , Denis Wittor

We have mapped 16 edge-on galaxies at 20 cm using the VLA. For 5 galaxies, we could form spectral index, energy and magnetic field maps. We find that all but one galaxy show evidence for non-thermal high latitude radio continuum emission,…

Astrophysics · Physics 2009-10-31 Judith A. Irwin , Jayanne English , Barkat Sorathia

We discuss production of very high energy (VHE) gamma-rays in large scale extragalactic jets of FR I sources. Based on recent optical and X-ray observations of these objects we evaluate their VHE emission in a framework of one electron…

Astrophysics · Physics 2007-05-23 L. Stawarz , M. Ostrowski , M. Sikora

We report the discovery of faint very high energy (VHE, E > 100 GeV) gamma-ray emission from the radio galaxy Centaurus A in deep observations performed with the H.E.S.S. experiment. A signal with a statistical significance of 5.0 sigma is…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-14 M. Raue , J. -P. Lenain , F. A. Aharonian , Y. Becherini , C. Boisson , A. -C. Clapson , L. Costamante , L. Gerard , C. Medina , M. de Naurois , M. Punch , F. Rieger , H. Sol , L. Stawarz , A. Zech

Dwarf galaxies, due to their shallow gravitational potentials, provide critical environments for studying feedback mechanisms from star formation and its impacts on dwarf galaxy evolution. In particular, radio continuum (RC) observations…

Very-high-energy (VHE, E \gtrsim 100 GeV) gamma rays emitted by extragalactic sources, such as blazars, initiate electromagnetic cascades in the intergalactic medium. The cascade photons arrive at the earth with angular and temporal…

High Energy Astrophysical Phenomena · Physics 2011-06-17 H. Huan , T. Weisgarber , T. Arlen , S. P. Wakely

Fast radio bursts (FRBs) are a recently discovered class of GHz-band, ms-duration, Jy-level-flux astrophysical transients, which origin is still a mystery. Exploring their gamma-ray counterpart is crucial for constraining their origin and…

High Energy Astrophysical Phenomena · Physics 2023-07-05 G. Principe , L. Di Venere , M. Negro , N. Di Lalla , N. Omodei , R. Di Tria , M. N. Mazziotta , F. Longo

The radio detection technique of cosmic ray air showers has gained renewed interest in the last two decades. While the radio experiments are very cost-effective to deploy, the Monte-Carlo simulations required to analyse the data are…

High Energy Astrophysical Phenomena · Physics 2024-01-17 Mitja Desmet , Stijn Buitink , Tim Huege , David Butler , Ralph Engel , Olaf Scholten

VHE (Very High Energy, E>100 GeV) radiation emitted at cosmological distances will pair produce on low-energy diffuse extragalactic background radiation before ever reaching us. This prevents us from directly seeing most of the VHE emission…

Astrophysics · Physics 2009-10-28 P. S. Coppi , F. A. Aharonian

The effects of kinetic whistler-wave instabilities on the runaway-electron (RE) avalanche is investigated. With parameters from DIII-D experiments, we show that RE scattering from excited whistler waves can explain several poorly understood…

We observed three $\gamma$-ray bursts related to thunderclouds in winter using the prototype of anti-neutrino detector PANDA made of 360-kg plastic scintillator deployed at Ohi Power Station at the coastal area of the Japan Sea. The maximum…

High Energy Astrophysical Phenomena · Physics 2016-05-18 Y. Kuroda , S. Oguri , Y. Kato , R. Nakata , Y. Inoue , C. Ito , M. Minowa