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We report the discovery of a pair of giant cavities, each nearly 200 kpc in diameter, embedded in the gaseous halo of the redshift z=0.216 galaxy cluster MS0735.6+7421. The cavities appear as surface brightness depressions in an image of…

天体物理学 · 物理学 2009-09-29 B. R. McNamara , P. E. J. Nulsen , M. W. Wise , D. A. Rafferty , C. Carilli , C. L. Sarazin , E. L. Blanton

The central regions of galaxy clusters are permeated by magnetic fields and filled with relativistic electrons. When clusters merge, the magnetic fields are amplified and relativistic electrons are re-accelerated by turbulence in the intra…

We report the detection of diffuse radio emission which might be connected to a large-scale filament of the cosmic web covering a 8deg x 8deg area in the sky, likely associated with a z~0.1 over-density traced by nine massive galaxy…

We present new low-frequency ($\nu = 88$-216 MHz) observations of the complex merging galaxy cluster Abell 3266. These new observations are taken with the Murchison Widefield Array (MWA) in its Phase II 'extended', long-baseline…

宇宙学与河外天体物理 · 物理学 2022-02-16 S. W. Duchesne , M. Johnston-Hollitt , C. J. Riseley , I. Bartalucci , S. R. Keel

Clusters of galaxies are excellent laboratories for studying recurring nuclear activity in galactic nuclei since their hot gaseous medium can vastly prolong the detectability of their radio lobes via better confinement. We report here a…

星系天体物理 · 物理学 2022-08-31 Sameer Salunkhe , Surajit Paul , Gopal-Krishna , Satish Sonkamble , Shubham Bhagat

We present the detection of a giant radio halo (GRH) in the Sunyaev-Zel'dovich (SZ)-selected merging galaxy cluster ACT-CL J0256.5+0006 ($z = 0.363$), observed with the Giant Metrewave Radio Telescope at 325 MHz and 610 MHz. We find this…

We report the discovery of a luminous, mini radio halo of ~240 kpc dimension at the center of a distant cluster of galaxies at redshift z = 0.131. Our optical and multi-wavelength GMRT and VLA observations reveal a highly unusual structure…

宇宙学与河外天体物理 · 物理学 2009-03-03 Joydeep Bagchi , Joe Jacob , Gopal-Krishna , Nitin Wadnerkar , J. Belapure , Norbert Werner , A. C. Kumbharkhane

Giant radio halos are mega-parsec scale synchrotron sources detected in a fraction of massive and merging galaxy clusters. Radio halos provide one of the most important pieces of evidence for non-thermal components in large scale structure.…

宇宙学与河外天体物理 · 物理学 2015-05-14 R. Cassano , G. Brunetti , H. J. A. Rottgering , M. Bruggen

ACO2163 is one of the hottest (mean $kT=12-15.5$ keV) and extremely X-ray overluminous merging galaxy clusters which is located at $z=0.203$. The cluster hosts one of the largest giant radio halos which are observed in most of the merging…

高能天体物理现象 · 物理学 2021-01-29 Nceba Mhlahlo , Loic Guennou , Luigina Feretti

(Abridged) The relaxed cool-core Phoenix cluster (SPT-CL J2344-4243) features an extremely strong cooling flow, as well as a mini-halo. Strong star-formation in the brightest cluster galaxy indicates that AGN feedback has been unable to…

宇宙学与河外天体物理 · 物理学 2021-02-03 R. Timmerman , R. J. van Weeren , M. McDonald , A. Ignesti , B. R. McNamara , J. Hlavacek-Larrondo , H. J. A. Röttgering

The radio continuum properties of galaxy clusters with cooling flows are reviewed along with the relationship to the X-ray environment. We find that 60-70% of cD galaxies in cooling flows are radio-loud, a much higher fraction than the 14%…

天体物理学 · 物理学 2007-05-23 Jack O. Burns , Chris Loken , Percy Gomez , Elizabeth Rizza , Mark Bliton , Michael Ledlow , Frazer Owen

We present Chandra gas temperature maps for two hot, intermediate-redshift clusters A665 and A2163. Both show strong temperature variations in their central r=1 Mpc regions, naturally interpreted as product of the subcluster mergers. The…

天体物理学 · 物理学 2011-05-05 M. Markevitch , A. Vikhlinin

The brightest cluster galaxy (BCG) in the majority of relaxed, cool core galaxy clusters is radio loud, showing non-thermal radio jets and lobes ejected by the central active galactic nucleus (AGN). Such relativistic plasma has been…

宇宙学与河外天体物理 · 物理学 2016-02-29 Myriam Gitti

The presence of non-thermal components in galaxy clusters is now clearly established. Diffuse radio emission from the Intra Cluster Medium (ICM) of several galaxy clusters is revealed in the form of radio halos and relics. These emissions…

宇宙学与河外天体物理 · 物理学 2009-02-18 Rossella Cassano

We present a weak-lensing analysis for the merging galaxy cluster, CIZA J2242.8+5301, hosting double radio relics, using three-band Subaru/Suprime-Cam imaging ($Br'z'$). Since the lifetime of dark matter halos colliding into clusters is…

宇宙学与河外天体物理 · 物理学 2015-10-07 Nobuhiro Okabe , Hiroki Akamatsu , Jun Kakuwa , Yutaka Fujita , Yu-Ying Zhang , Masayuki Tanaka , Keiichi Umetsu

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…

宇宙学与河外天体物理 · 物理学 2021-04-26 J. M. Boxelaar , R. J. van Weeren , A. Botteon

Aims. We present the first results of an ongoing project devoted to the search of giant radio halos in galaxy clusters located in the redshift range z=0.2--0.4. One of the main goals of our study is to measure the fraction of massive galaxy…

天体物理学 · 物理学 2009-11-11 T. Venturi , S. Giacintucci , G. Brunetti , R. Cassano , S. Bardelli , D. Dallacasa , G. Setti

About 1/3 of X-ray-luminous clusters show smooth, unpolarized radio emission on ~Mpc scales, known as giant radio halos. One promising model for radio halos is Fermi-II acceleration of seed relativistic electrons by turbulence of the…

高能天体物理现象 · 物理学 2015-03-30 Anders Pinzke , S. Peng Oh , Christoph Pfrommer

Merging galaxy clusters often host spectacular diffuse radio synchrotron sources. These sources can be explained by a non-thermal pool of relativistic electrons accelerated by shocks and turbulence in the intracluster medium. The origin of…

We calculate the probability to form giant radio halos (~ 1 Mpc size) as a function of the mass of the host clusters by using a Statistical Magneto-Turbulent Model (Cassano & Brunetti, these proceedings). We show that the expectations of…

天体物理学 · 物理学 2015-06-24 Rossella Cassano , Gianfranco Brunetti , Giancarlo Setti