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Annihilation of Dark Matter usually produces together with gamma rays comparable amounts of electrons and positrons. The e+e- gyrating in the galactic magnetic field then produce secondary synchrotron radiation which thus provides an…

Astrophysics · Physics 2009-08-19 Enrico Borriello , Alessandro Cuoco , Gennaro Miele

Radio continuum observations of external galaxies provide us with an excellent outside view on the distribution of cosmic-ray electrons in the disc and halo. In this review, we summarise the current state of what we have learned from…

Astrophysics of Galaxies · Physics 2021-12-16 Volker Heesen

We use results from a constrained, cosmological MHD simulation of the Local Universe to predict radio halos and their evolution for a volume limited set of galaxy clusters and compare to current observations. The simulated magnetic field…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 J. Donnert , K. Dolag , R. Cassano , G. Brunetti

Diffuse synchrotron radio emission from cosmic-ray electrons is observed at the center of a number of galaxy clusters. These sources can be classified either as giant radio halos, which occur in merging clusters, or as mini halos, which are…

The leaky box model is now ruled out by measurements of a cosmic ray gradient throughout the galactic disk. It needs to be replaced by a more refined treatment which takes into account the diffusion of cosmic rays in the magnetic fields of…

Astrophysics · Physics 2009-10-28 P. Chardonnet , G. Mignola , P. Salati , R. Taillet

We calculate the flux of radio, hard X-ray and UV radiation from clusters of galaxies as produced by synchrotron emission and Inverse Compton Scattering of electrons generated as secondaries in cosmic ray interactions in the intracluster…

Astrophysics · Physics 2011-08-09 P. Blasi , S. Colafrancesco

Interstellar synchrotron emission depends on Galactic magnetic fields and on cosmic-ray leptons. Observations of radio emission are an important tool for studying cosmic-ray propagation models and interstellar electron spectrum and…

Astrophysics of Galaxies · Physics 2013-07-24 Elena Orlando , Andrew W. Strong

A recent re-analysis of EGRET data by Dixon et al. has led to the discovery of a statistically significant diffuse $\gamma$-ray emission from the galactic halo. We show that this emission can naturally be accounted for within a…

Astrophysics · Physics 2007-05-23 F. De Paolis , G. Ingrosso , Ph. Jetzer , M. Roncadelli

Context: The relation between Galactic cosmic-ray electrons, magnetic fields and synchrotron radiation. Aims: We exploit synchrotron radiation to constrain the low-energy interstellar electron spectrum, using various radio surveys and…

High Energy Astrophysical Phenomena · Physics 2011-10-03 A. W. Strong , E. Orlando , T. R. Jaffe

Recent evidence for a large Galactic halo, based on cosmic-ray radioactive nuclei, implies a significant contribution from inverse Compton emission at high Galactic latitudes. We present predictions for the expected intensity distribution,…

Astrophysics · Physics 2007-05-23 A. W. Strong , I. V. Moskalenko , O. Reimer

Various studies have implied the existence of a gaseous halo around the Galaxy extending out to 100 kpc. Galactic cosmic rays (CRs) that propagate to the halo, either by diffusion or by convection with the possibly existing large-scale…

High Energy Astrophysical Phenomena · Physics 2019-01-30 Ruo-Yu Liu , Huirong Yan , Xiang-Yu Wang , Shi Shao , Hui Li

Fluctuations in the Galactic synchrotron emission can be traced by the angular power spectrum of radio maps at low multipoles. At frequencies below few GHz, large-scale anisotropies are mainly induced by magnetic field turbulence. By…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Marco Regis

The Galactic secondary cosmic ray anti-proton flux calculated with different propagation models is fairly consistent with data, and the associated propagation uncertainty is small. This is not the case for any anti-proton exotic component…

Astrophysics · Physics 2007-05-23 D. Maurin , R. Taillet , C. Combet

Here we present Halo-FDCA, a robust open source Python package for modeling and estimating total flux densities of radio (mini) halos in galaxy clusters. Radio halos are extended ( ~200 - 1500 kpc in size) synchrotron emitting sources found…

Cosmology and Nongalactic Astrophysics · Physics 2021-04-26 J. M. Boxelaar , R. J. van Weeren , A. Botteon

Giant radio halos are diffuse, Mpc-scale, synchrotron sources located in the central regions of galaxy clusters and provide the most relevant example of cluster non-thermal activity. Radio and X-ray surveys allow to investigate the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 G. Brunetti , R. Cassano , K. Dolag , G. Setti

In the present paper we construct maps of polarized synchrotron radio emission of a whole galaxy, based on local models of the cosmic ray (CR) driven dynamo. We perform numerical simulations of the dynamo in local Cartesian domains, with…

Cosmic ray nuclei fluxes are expected to be measured with high precision in the near future. For instance, high quality data on the antiproton component could give important clues about the nature of the astronomical dark matter. A very…

Astrophysics · Physics 2008-11-26 D. Maurin , F. Donato , R. Taillet , P. Salati

Observations of giant radio halos provide unambiguous evidence for the existence of cosmic ray (CR) electrons and magnetic fields in galaxy clusters. The physical mechanism generating radio halos is still heavily debated. We critically…

High Energy Astrophysical Phenomena · Physics 2011-09-28 Christoph Pfrommer , Torsten Ensslin , Francesco Miniati , Kandaswamy Subramanian

We combine all available information about the spectral shape and morphology of the radio halo of the Coma cluster with the gamma-ray upper limits obtained by the Fermi-LAT and with the magnetic field strength derived from Faraday rotation…

High Energy Astrophysical Phenomena · Physics 2015-06-05 G. Brunetti , P. Blasi , O. Reimer , L. Rudnick , A. Bonafede , S. Brown

We consider the synchrotron emission from electrons out in the Galactic halo bubble region where the Fermi bubble structures reside. Utilising a simple analytical expression for the non-thermal electron distribution and a toy magnetic field…

High Energy Astrophysical Phenomena · Physics 2022-10-04 Vasundhara Shaw , Arjen van Vliet , Andrew M. Taylor