Radio observations of ZwCl 2341.1+0000:  a double radio relic cluster

Weeren, R. J. van; Röttgering, H. J. A.; Bagchi, J.; Raychaudhury, Somak; Intema, H. T.; Miniati, Francesco; Enßlin, T. A.; Markevitch, M.; Erben, T.

doi:10.1051/0004-6361/200912287

Cited by 76 publications

(87 citation statements)

References 63 publications

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“…This one is the second-most massive cluster in the supercluster region. The faint, non-thermal synchrotron radio emission on a Mpc scale discovered in the ZwCl 2341.1+0000 cluster (Bagchi et al 2002;van Weeren et al 2009;Giovannini et al 2010) is a clear signpost of the infall and merger dynamics of several galaxy groups during the first phase of the cluster formation process (Boschin et al 2013). The optical images of clusters Abell 2631 and ZwCl 2341.1+0000 are shown in Figure 12.…”

Section: Mass Distributionmentioning

confidence: 94%

Saraswati: An Extremely Massive ∼200 Megaparsec Scale Supercluster

Sankhyayan

Sarkar

Raychaudhury

et al. 2017

ApJ

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Here we report the discovery of an extremely massive and large supercluster (called Saraswati a) ) found in the Stripe 82 region of SDSS. This supercluster is a major concentration of galaxies and galaxy clusters, forming a wall-like structure spanning at least 200 Mpc across at the redshift z ≈ 0.3. This enormous structure is surrounded by a network of galaxy filaments, clusters, and large, ∼ 40−170 Mpc diameter, voids. The mean density contrast δ (relative to the background matter density of the universe) of Saraswati is 1.62 and the main body of the supercluster comprises at least 43 massive galaxy clusters (mean z = 0.28) with a total mass of ∼ 2×1016 M ⊙ . The spherical collapse model suggests that the central region of radius ∼ 20 Mpc and mass at least 4 × 10 15 M ⊙ may be collapsing. This places it among the few largest and most massive superclusters known, comparable to the most massive 'Shapley Concentration' (z ≈ 0.046) in the nearby universe. The Saraswati supercluster and its environs reveal that some extreme large-scale, prominent matter density enhancements had formed ∼ 4 Gy in the past when dark energy had just started to dominate structure formation. This galactic concentration sheds light on the role of dark energy and cosmological initial conditions in supercluster formation, and tests the competing cosmological models.

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Section: Mass Distributionmentioning

confidence: 94%

Saraswati: An Extremely Massive ∼200 Megaparsec Scale Supercluster

Sankhyayan

Sarkar

Raychaudhury

et al. 2017

ApJ

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“…A few clusters host so-called double relics systems (van Weeren et al 2011a;van Weeren et al 2010;Bonafede et al 2009b;van Weeren et al 2009a;Venturi et al 2007;Feretti et al 2005;Bagchi et al 2006;Röttgering et al 1997), with both relics located symmetrically about to the cluster center and along the merger axis, as indicated by X-ray observations of the thermal ICM. Another class of diffuse filamentary radio sources in clusters are radio "phoenices".…”

Section: Introductionmentioning

confidence: 99%

Radio continuum observations of new radio halos and relics from the NVSS and WENSS surveys

Weeren

Brüggen

Röttgering

et al. 2011

A&A

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118

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Context. Radio halos and relics are diffuse radio sources found in galaxy clusters showing significant substructure at X-ray wavelengths. These sources provide important information about non-thermal processes taking place in the intracluster medium (ICM). Until now only a few dozen relics and halos are known, while models predict that a much larger number of these sources exist. In this paper we present the results of an extensive observing campaign to search for new diffuse radio sources in galaxy clusters. Aims. The aim of the observations is to create a large sample of diffuse radio sources in galaxy clusters that help to understand the formation of radio relics and halos and can be used to probe the physical conditions of the ICM. Methods. We carried out radio continuum observations with the Westerbork Synthese Radio Telescope (WSRT), Giant Metrewave Radio Telescope (GMRT) and Very Large Array (VLA) of clusters with diffuse radio emission visible in NVSS and WENSS survey images. Optical images were taken with the William Herschel and Isaac Newton Telescope (WHT, INT). Results. We discovered 6 new radio relics, including a probable double relic system, and 2 radio halos. In addition, we confirm the presence of diffuse radio emission in four galaxy clusters. By constructing a sample of 35 radio relics we find that relics are mostly found along the major axis of the X-ray emission from the ICM, while their orientation is perpendicular to this axis. We also compared the X-ray luminosity and redshift distributions of clusters with relics to an X-ray selected sample from the NORAS and REFLEX surveys. We find tentative evidence for an increase of the cluster's relic fraction with X-ray luminosity and redshift. The major and minor axis ratio distribution of the ICM for clusters with relics is broader than that of the NORAS-REFLEX sample. Conclusions. The location and orientation of radio relics with respect to the ICM elongation is consistent with the scenario that relics trace merger shock waves.

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“…They probably trace shock fronts in which particles are accelerated via the diffusive shock acceleration mechanism (DSA; Krymskii 1977;Axford et al 1977;Bell 1978a,b;Blandford & Ostriker 1978;Drury 1983;Blandford & Eichler 1987;Jones & Ellison 1991;Malkov & O'C Drury 2001). Among these are rare double-relics that have two relics located on both sides of the cluster center (e.g., Bonafede et al 2009b;van Weeren et al 2009avan Weeren et al , 2010Venturi et al 2007;Bagchi et al 2006;Röttgering et al 1997;Brown et al 2010). According to DSA theory, the integrated radio spectrum should be a single power-law.…”

Section: Introductionmentioning

confidence: 99%

Diffuse steep-spectrum sources from the 74 MHz VLSS survey

Weeren

Röttgering

Brüggen

2011

A&A

Self Cite

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Context. Galaxy clusters grow by a sequence of mergers with other clusters and galaxy groups. During these mergers, shocks and/or turbulence are created within the intracluster medium (ICM). In this process, particles could be accelerated to highly relativistic energies. The synchrotron radiation from these particles is observed in the form of radio relics and halos that are generally characterized by a steep radio spectral index. Shocks can also revive fossil radio plasma from a previous episode of AGN activity, creating a socalled radio "phoenix". Here we present multi-frequency radio observations of diffuse steep-spectrum radio sources selected from the 74 MHz VLSS survey. Previous Giant Metrewave Radio Telescope (GMRT) observations showed that some of these sources had filamentary and elongated morphologies, which are expected for radio relics. Aims. We attempt to understand the nature of diffuse steep-spectrum radio sources and characterize their spectral index and polarization properties. Methods. We carried out radio continuum observations at 325 MHz with the GMRT. Observations with the Very Large Array (VLA) and Westerbork Synthesis Radio Telescope (WSRT) were taken at 1.4 GHz in full polarization mode. Optical images around the radio sources were taken with the William Herschel and Isaac Newton Telescope (WHT, INT). Results. Most of the sources in our sample consist of old radio plasma from AGNs located in small galaxy clusters. The sources can be classified as AGN relics or radio phoenices. The spectral indices across most of the radio sources display large variations. Conclusions. We conclude that diffuse steep-spectrum radio sources are not only found in massive X-ray luminous galaxy clusters but also in smaller systems. Future low-frequency surveys will uncover large numbers of steep-spectrum radio relics related to previous episodes of AGN activity.

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Radio observations of ZwCl 2341.1+0000: a double radio relic cluster

Cited by 76 publications

References 63 publications

Saraswati: An Extremely Massive ∼200 Megaparsec Scale Supercluster

Saraswati: An Extremely Massive ∼200 Megaparsec Scale Supercluster

Radio continuum observations of new radio halos and relics from the NVSS and WENSS surveys

Diffuse steep-spectrum sources from the 74 MHz VLSS survey

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