VLA observations of the rich X-ray cluster Abell 2256

Röttgering, H. J. A.; Snellen, I. A. G.; Miley, G. K.; Jong, J.P. de; Hanisch, R. J.; Perley, R. A.

doi:10.1086/174940

Cited by 80 publications

(125 citation statements)

References 0 publications

Supporting

Mentioning

116

Contrasting

Order By: Relevance

“…We adopt the radio source labeling from Bridle & Fomalont (1976) and Röttgering et al (1994). The 325 MHz GMRT image ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…At radio wavelengths, the cluster shows a very complex morphology. The cluster is known to host a bright peripheral radio relic, a radio halo, a number of complex relatively compact filamentary sources, and several "head-tail" sources (Bridle & Fomalont 1976;Bridle et al 1979;Röttgering et al 1994;Miller et al 2003;Clarke & Ensslin 2006;Brentjens 2008).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The discovery of diffuse steep spectrum sources in Abell 2256

Weeren

Intema

Oonk

et al. 2009

A&A

View full text Add to dashboard Cite

Context. Hierarchical galaxy formation models indicate that during their lifetime galaxy clusters undergo several mergers. An example of such a merging cluster is Abell 2256. Here we report on the discovery of three diffuse radio sources in the periphery of Abell 2256, using the Giant Metrewave Radio Telescope (GMRT). Aims. The aim of the observations was to search for diffuse ultra-steep spectrum radio sources within the galaxy cluster Abell 2256. Methods. We have carried out GMRT 325 MHz radio continuum observations of Abell 2256. V, R and I band images of the cluster were taken with the 4.2 m William Herschel Telescope (WHT). Results. We have discovered three diffuse elongated radio sources located about 1 Mpc from the cluster center. Two are located to the west of the cluster center, and one to the southeast. The sources have a measured physical extent of 170, 140 and 240 kpc, respectively. The two western sources are also visible in deep low-resolution 115-165 MHz Westerbork Synthesis Radio Telescope (WSRT) images, although they are blended into a single source. For the combined emission of the blended source we find an extreme spectral index (α) of −2.05 ± 0.14 between 140 and 351 MHz. The extremely steep spectral index suggests these two sources are most likely the result of adiabatic compression of fossil radio plasma due to merger shocks. For the source to the southeast, we find that α < −1.45 between 1369 and 325 MHz. We did not find any clear optical counterparts to the radio sources in the WHT images. Conclusions. The discovery of the steep spectrum sources implies the existence of a population of faint diffuse radio sources in (merging) clusters with such steep spectra that they have gone unnoticed in higher frequency ( > ∼ 1 GHz) observations. Simply considering the timescales related to the AGN activity, synchrotron losses, and the presence of shocks, we find that most massive clusters should possess similar sources. An exciting possibility therefore is that such sources will determine the general appearance of clusters in low-frequency high resolution radio maps as will be produced by for example LOFAR or LWA.

show abstract

“…We adopt the radio source labeling from Bridle & Fomalont (1976) and Röttgering et al (1994). The 325 MHz GMRT image ( Fig.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The discovery of diffuse steep spectrum sources in Abell 2256

Weeren

Intema

Oonk

et al. 2009

A&A

View full text Add to dashboard Cite

show abstract

“…Miller et al (2003) identified the radio sources associated with member galaxies of Abell 2256. Each radio source is labeled with alphabets (Bridle & Fomalont 1976;Bridle et al 1979;Rottgering et al 1994), and Sources A, B, and C are the remarkable bright sources. Sources A and B are linearly polarized sources which are suitable for our measuring RMs.…”

Section: Cluster Of Galaxies Abell 2256mentioning

confidence: 99%

“…Sources A and B are linearly polarized sources which are suitable for our measuring RMs. Source C is known as a head-tail galaxy which has a narrow straight tail extending for at least 480 kpc at 1.4 GHz across the radio relic (Rottgering et al 1994). …”

Section: Cluster Of Galaxies Abell 2256mentioning

confidence: 99%

See 1 more Smart Citation

JVLA S- and X-band polarimetry of the merging cluster Abell 2256

Ozawa

Nakanishi

Akahori

et al. 2015

Publications of the Astronomical Society of Japan

View full text Add to dashboard Cite

We report polarimetry results of a merging cluster of galaxies Abell 2256 with Karl G. Jansky Very Large Array (JVLA). We performed new observations with JVLA at S-band (2051-3947 MHz) and X-band (8051-9947 MHz) in the C array configuration, and detected significant polarized emissions from the radio relic, Source A, and Source B in this cluster. We calculated the total magnetic field strengths toward the radio relic using revised equipartition formula, which is 1.8-5.0 µG. With dispersions of Faraday rotation measure, magnetic-field strengths toward Sources A and B are estimated to be 0.63-1.26 µG and 0.11-0.21 µG, respectively. An extremely high degree of linear polarization, as high as ∼ 35 %, about a half of the maximum polarization, was detected toward the radio relic, which indicates highly ordered magnetic lines of force over the beam sizes (∼ 52 kpc).The fractional polarization of the radio relic decreases from ∼ 35 % to ∼ 20 % around 3 GHz as the frequency decreases and is nearly constant between 1.37 and 3 GHz. Both analyses with depolarization models and Faraday tomography suggest multiple depolarization components toward the radio relic and imply the existence of turbulent magnetic fields.

show abstract

Mergers, relics and magnetic fields: The complex case of A2256

Enßlin¹

2006

Astron Nachr

View full text Add to dashboard Cite

Clusters of galaxies undergo multiple mergers during their lifetimes. Each merger drives shocks into the intracluster medium (ICM) which can heat the thermal gas, accelerate relativistic particles, and compress magnetic fields. Radio observations toward a number of clusters reveal large regions of diffuse synchrotron emission (halos and relics) which are not associated with individual host galaxies but are general properties of the ICM. Clusters host to this diffuse emission reveal significant evidence of recent or on-going merger activity. We present deep VLA observations of the diffuse radio halo and relic emission in Abell 2256. Our new observations provide the first detailed image of the central diffuse radio halo emission in this cluster. The high fractional polarization of the relic allow us to use Faraday rotation measure observations to place constraints on the merger geometry of the system. In addition, the relic is composed of a number of synchrotron filaments which suggest the presence of spatially intermittent magnetic fields in this cluster.

show abstract

VLA observations of the rich X-ray cluster Abell 2256

Cited by 80 publications

References 0 publications

The discovery of diffuse steep spectrum sources in Abell 2256

The discovery of diffuse steep spectrum sources in Abell 2256

JVLA S- and X-band polarimetry of the merging cluster Abell 2256

Mergers, relics and magnetic fields: The complex case of A2256

Contact Info

Product

Resources

About