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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 polarized component of the diffuse radio synchrotron emission of our Galaxy shows structure, which is apparently unrelated to the structure in total intensity, on many scales. The structure in the polarized emission can be due to…

Astrophysics · Physics 2009-11-10 M. Haverkorn , P. Katgert , A. G. de Bruyn

We present optical spectropolarimetric and imaging polarimetric observations of four high-redshift radio galaxies (HzRGs) obtained with the 10-m Keck I telescope. A broad Mg II emission line is detected in the total and polarized flux…

A number of relaxed, cool-core galaxy clusters exhibit diffuse, steep-spectrum radio sources in their central regions, known as radio mini-halos. It has been proposed that the relativistic electrons responsible for the emission have been…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 John ZuHone , Maxim Markevitch , Gianfranco Brunetti , Simona Giacintucci

The main component of the intracluster medium (ICM) in clusters of galaxies is represented by the X-ray emitting thermal plasma. In addition, the presence of relativistic electrons and large-scale magnetic fields in a fraction of galaxy…

Astrophysics · Physics 2007-05-23 L. Feretti

In inhomogeneous optically thick synchrotron sources a substantial part of the electron population at low energies can be hidden by self-absorption and overpowered by high energy electrons in optically thin emission. These invisible…

Astrophysics · Physics 2009-11-07 Thomas Beckert , Heino Falcke

The number of diffuse radio halos in clusters of galaxies has grown in recent years, making it possible to derive statistical properties of these sources and of the hosting clusters. We show that diffuse sources are associated with X-ray…

Astrophysics · Physics 2007-05-23 L. Feretti , G. Brunetti , G. Giovannini , F. Govoni , G. Setti

Time-resolved optical and infrared polarimetric observations of black hole and neutron star low-mass X-ray binaries are presented. Data were acquired with the VLT, UKIRT and HIPPO on the SAAO 1.9-m. We find that for some sources in…

High Energy Astrophysical Phenomena · Physics 2015-03-19 David M. Russell , Piergiorgio Casella , Rob Fender , Paolo Soleri , Magaretha L. Pretorius , Fraser Lewis , Michiel van der Klis

We present an MHD simulation of the emergence of a radio minihalo in a galaxy cluster core in a "secondary" model, where the source of the synchrotron-emitting electrons is hadronic interactions between cosmic-ray protons with the thermal…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 John ZuHone , Gianfranco Brunetti , Simona Giacintucci , Maxim Markevitch

The structure of magnetic fields in galaxies remains poorly constrained, despite the importance of magnetism in the evolution of galaxies. Radio synchrotron and far-infrared (FIR) polarization and polarimetric observations are the best…

Cosmological simulations predict the presence of warm hot thermal gas in the cosmic filaments that connect galaxy clusters. This gas is thought to constitute an important part of the missing baryons in the Universe. In addition to the…

Radio halos are synchrotron radio sources detected in some massive galaxy clusters. Their Mpc-size indicates that (re)acceleration processes are taking place in the host cluster. X-ray catalogues of galaxy clusters have been used in the…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-28 A. Bonafede , H. T. Intema , M. Brüggen , F. Vazza , K. Basu , M. Sommer , H. Ebeling , F. de Gasperin , H. J. A. Röttgering , R. J. van Weeren , R. Cassano

The organization of this paper is as follows: the basic formulae used to derive the age of synchrotron sources and the equipartition parameters are presented in Section 2, while the observational properties of diffuse radio sources (Radio…

Astrophysics · Physics 2015-06-24 Luigina Feretti , Gabriele Giovannini

(Abridged) We study the polarisation properties, magnetic field strength, and synchrotron emission scale-height of Milky-Way-like galaxies in comparison with other spiral galaxies. We use our 3D-emission model of the Milky Way Galaxy for…

Astrophysics of Galaxies · Physics 2015-06-05 X. H. Sun , W. Reich

(Abridged) We constrain simulated all-sky maps in total intensity, linear polarization, and rotation measure (RM) by observations. We test a number of large-scale magnetic field configurations and take the properties of the warm…

Astrophysics · Physics 2009-11-13 X. H. Sun , W. Reich , A. Waelkens , T. Enßlin

We report on new 1.41 GHz Green Bank Telescope and 352 MHz Westerbork Synthesis Radio Telescope observations of the Coma cluster and its environs. At 1.41 GHz we tentatively detect an extension to the Coma cluster radio relic source…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Shea Brown , Lawrence Rudnick

We present LOFAR $120-168$ MHz images of the merging galaxy cluster Abell 1240 that hosts double radio relics. In combination with the GMRT $595-629$ MHz and VLA $2-4$ GHz data, we characterised the spectral and polarimetric properties of…

Radio observations can show how cluster galaxies are affected by various environmental factors. We made three frequency radio-polarimetric VLA observations and performed sensitive XMM-Newton observations in X-rays and UV light of NGC4254.…

Astrophysics · Physics 2009-11-13 K. T. Chyzy , M. Ehle , R. Beck

Polarization measurements at low radio frequencies allow detection of small Faraday rotation measures caused by regular magnetic fields in galaxies and in the foreground of the Milky Way. The galaxy M31 was observed in two overlapping…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 René Gießübel , George Heald , Rainer Beck , Tigran Arshakian

Merger shocks induce turbulence in the intra-cluster medium (ICM), and, under some circumstances, accelerate electrons to relativistic velocities to form so-called radio relics. Relics are mostly found at the periphery of galaxy clusters…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-18 Luigi Iapichino , Marcus Brüggen