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Galaxy cluster mass distributions are useful probes of Omega_0 and the nature of the dark matter. Large clusters will distort the observed shapes of background galaxies through gravitational lensing allowing the measurement of the cluster…

天体物理学 · 物理学 2009-10-31 Philippe Fischer

We report the discovery of a putative radio relic, 830 kpc in length and found toward the outskirts of galaxy cluster Abell 1697 ($z=0.181$), using the LOFAR Two Meter Sky Survey (LoTSS) at 144 MHz. With an X-ray-inferred mass of…

星系天体物理 · 物理学 2020-01-15 Surajit Paul , Sameer Salunkhe , Satish Sonkamble , Prateek Gupta , Tony Mroczkowski , Somak Raychaudhury

The globular cluster Omega Centauri is the most massive and luminous cluster in the Galaxy. The $\gamma$-ray source FL8Y J1326.7$-$4729 is coincident with the core of the cluster, leading to speculation that hitherto unknown radio pulsars…

高能天体物理现象 · 物理学 2020-01-15 Shi Dai , Simon Johnston , Matthew Kerr , Fernando Camilo , Andrew Cameron , Lawrence Toomey , Hiroki Kumamoto

Context. It is well-established that shock waves in the intracluster medium launched by galaxy cluster mergers can produce synchrotron emission, which is visible to us at radio frequencies as radio relics. However, the particle acceleration…

A series of new radio-continuum (lambda=20 cm) mosaic images focused on the NGC 300 galactic system were produced using archived observational data from the VLA and/or ATCA. These new images are both very sensitive (rms=60 microJy) and…

We study the impact of cluster environment on the morphology of a sample of 4304 extended radio galaxies from Radio Galaxy Zoo. A total of 87% of the sample lies within a projected 15 Mpc of an optically identified cluster. Brightest…

We present results on 12 X-ray bright clusters observed at 1.4 GHz with the Green Bank Telescope. After subtraction of point sources, we reach a median (best) 1-sigma noise level of 0.01 (0.006) microJy/sq. arcsec, and find a significant…

宇宙学与河外天体物理 · 物理学 2015-06-17 Damon Farnsworth , Lawrence Rudnick , Shea Brown , Gianfranco Brunetti

We present high-angular-resolution radio observations of the Arches cluster in the Galactic centre, one of the most massive young clusters in the Milky Way. The data were acquired in two epochs and at 6 and 10 GHz with the Karl G. Jansky…

We derive the best characterization to date of the properties of radio quiescent massive galaxy clusters through a statistical analysis of their average synchrotron emissivity. We stacked 105 radio images of clusters from the 843 MHz SUMSS…

宇宙学与河外天体物理 · 物理学 2015-05-30 Shea Brown , Andrew Emerick , Lawrence Rudnick , Gianfranco Brunetti

Galaxy cluster mass distribution are potentially useful probes of $\Omega_0$ and the nature of the dark matter. Large clusters will distort the observed shapes of background galaxies through gravitational lensing allowing the measurement of…

天体物理学 · 物理学 2016-08-30 Philippe Fischer , J. Anthony Tyson

Hidden from optical view in the starburst region of the dwarf galaxy NGC 5253 lies an intense radio source with an unusual spectrum which could be interpreted variously as nebular gas ionized by a young stellar cluster or nonthermal…

天体物理学 · 物理学 2009-11-06 Varoujan Gorjian , Jean L. Turner , Sara C. Beck

We present the results of a search for X--ray luminous distant clusters of galaxies. We found extended X--ray emission characteristic of a cluster towards two of our candidate clusters of galaxies. They both have a luminosity in the ROSAT…

天体物理学 · 物理学 2009-10-22 R. C. Nichol , M. P. Ulmer , R. G. Kron , G. D. Wirth , D. C. Koo

Globular clusters are found usually in galaxies and they are an excellent tracer of dark matter. Long ago it was suggested that there may exist intracluster globular clusters (IGCs) bound to a galaxy cluster rather than to any single…

宇宙学与河外天体物理 · 物理学 2015-05-18 Myung Gyoon Lee , Hong Soo Park , Ho Seong Hwang

Clusters of galaxies are sites of acceleration of charged particles and sources of non-thermal radiation. We report on new constraints on the population of cosmic rays in the Intra Cluster Medium (ICM) obtained via radio observations of a…

天体物理学 · 物理学 2009-11-13 G. Brunetti , T. Venturi , D. Dallacasa , R. Cassano , K. Dolag , S. Giacintucci , G. Setti

We report on our search for distant clusters of galaxies based on optical and X-ray follow up observations of X-ray candidates from the SHARC survey. Based on the assumption that the absence of bright optical or radio counterparts to…

天体物理学 · 物理学 2009-11-13 C. Adami , M. P. Ulmer , F. Durret , G. Covone , E. Cypriano

In this paper we present weak lensing observations of the fields around 8 z~1 luminous radio sources. These data are searched for the lensing signatures of clusters that are either physically associated with the radio objects, or are…

天体物理学 · 物理学 2015-06-24 Richard G. Bower , Ian Smail

VLA B-configuration snapshots have been obtained at 6cm and 20cm of 43 radio quasars with a range of known galaxy cluster environments. The radio sources are characterised by measures of morphology, flux, and size. These are studied as a…

天体物理学 · 物理学 2009-10-28 J. B. Hutchings , A. C. Gower , S. Ryneveld , A. Dewey

A weak-lensing analysis of wide-field $V$- and $I$-band images centered on the cluster Abell 1942 has uncovered a mass concentration $\sim 7$ arcminutes South of the cluster center. A statistical analysis shows that the detections are…

We report on the progress of our search for serendipitous distant X-ray galaxy clusters in the ROSAT PSPC pointed observations archive. The initial aim of our work is to measure the X-ray luminosity function of clusters down to 4 x 10^-14…

天体物理学 · 物理学 2007-05-23 D. J. Burke , C. A. Collins , R. C. Nichol , A. K. Romer , B. Holden , R. M. Sharples , M. P. Ulmer

We present a catalog of 246 radio sources found in the central 1 degree of the COSMOS field at 1.4GHz. The VLA pilot project data have a resolution of 1.9"x1.6" and an rms noise limit of ~25-100uJy/beam covering 0.837 sqrdeg. About 20 radio…