The discovery of diffuse steep spectrum sources in Abell 2256

Weeren, R. J. van; Intema, H. T.; Oonk, J. B. R.; Röttgering, H. J. A.; Clarke, T. E.

doi:10.1051/0004-6361/200912934

Cited by 29 publications

(30 citation statements)

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“…They reveal many new details in the relic and show that the relic has a significant amount of filamentary structure on scales down to ∼30kpc. Small-scale filamentary structures have also been seen for other relics, such as the Toothbrush cluster (van Weeren et al , 2016a, A3667 (Röttgering et al 1997), A3376 (Bagchi et al 2006), and in particular for Abell2256 (Clarke & Enßlin 2006;van Weeren et al 2009a;Owen et al 2014).…”

Section: Continuum Imagesmentioning

confidence: 83%

“…These fossil electrons could, for example, originate from the (old) lobes of radio galaxies. Indeed, observations provide some support for this scenario because of the complex morphologies of some relics, suggesting a link with a nearby radio galaxy in a few select cases (Giovannini et al 1991;van Weeren et al 2013;Bonafede et al 2014;Shimwell et al 2015). The most compelling case for re-acceleration has been found in the merging cluster Abell3411-3412 (van Weeren et al 2017).…”

Section: Acceleration Mechanismsmentioning

confidence: 99%

“…Vazza & Brüggen (2014) andVazza et al (2015 show that the observed γ-rayupper limits are in tension with the relative acceleration efficiency of electrons and protons that is expected from DSA. Tension with DSA has also been found from the discrepancy between the measured Mach numbers from X-ray observations and the radio spectral index (see Equation (3)) for some relics (e.g., Akamatsu et al 2015;Itahana et al 2015;van Weeren et al 2016a).…”

Section: Acceleration Mechanismsmentioning

confidence: 99%

“…A problem with this scenario is that shocks in clusters generally have Mach number of   3and the acceleration of electrons from the thermal pool is thought to be very inefficient for these low Mach numbers, in apparent conflict with the presence of bright radio relics. In this case, an unrealistic fraction of the energy flux through the shock surface (Macario et al 2011;Eckert et al 2016;van Weeren et al 2016a) needs to be converted to the non-thermal electron population.…”

Section: Acceleration Mechanismsmentioning

confidence: 99%

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Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

Weeren

Ogrean

Jones

et al. 2017

ApJ

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To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandraobservations of the HST Frontier Fields cluster MACSJ0717.5+3745. The Chandraimage shows a complex merger event, with at least four components belonging to different merging subclusters. Northwestof the cluster, ∼0.7 Mpc from the center, there is a ram-pressure-stripped core that appears to have traversed the densest parts of the cluster after entering the intracluster medium (ICM) from the direction of a galaxy filament to the southeast. We detect a density discontinuity north-northeastof this core, which we speculate is associated with a cold front. Our radio images reveal new details for the complex radio relic and radio halo in this cluster. In addition, we discover several new filamentary radio sources with sizes of 100-300kpc. A few of these seem to be connected to the main radio relic, while others are either embedded within the radio halo or projected onto it. A narrow-angled-tailed (NAT) radio galaxy, a cluster member, is located at the center of the radio relic. The steep spectrum tails of this active galactic nucleuslead into the large radio relic where the radio spectrum flattens again. This morphological connection between the NAT radio galaxy and relic provides evidence for reacceleration (revival) of fossil electrons. The presence of hot 20 keV ICM gas detected by Chandranear the relic location provides additional support for this re-acceleration scenario.

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Section: Continuum Imagesmentioning

confidence: 83%

Section: Acceleration Mechanismsmentioning

confidence: 99%

Section: Acceleration Mechanismsmentioning

confidence: 99%

Section: Acceleration Mechanismsmentioning

confidence: 99%

See 2 more Smart Citations

Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

Weeren

Ogrean

Jones

et al. 2017

ApJ

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“…[4,2,10,17,12]). This cluster was observed with LOFAR in the HBA band (115 − 165 MHz) in May 2010 for about 8 hours.…”

Section: Abell 2256mentioning

confidence: 99%

Recent LOFAR imaging pipeline results

Heald

McKean

Pizzo

et al. 2010

Proceedings of ISKAF2010 Science Meeting — PoS(ISKAF2010)

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on behalf of the LOFAR CollaborationOne of the science drivers of the new Low Frequency Array (LOFAR) is large-area surveys of the low-frequency radio sky. Realizing this goal requires automated processing of the interferometric data, such that fully calibrated images are produced by the system during survey operations. The LOFAR Imaging Pipeline is the tool intended for this purpose, and is now undergoing significant commissioning work. The pipeline is now functional as an automated processing chain. Here we present several recent LOFAR images that have been produced during the still ongoing commissioning period. These early LOFAR images are representative of some of the science goals of the commissioning team members.

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Diffuse Radio Emission from Galaxy Clusters

et al. 2019

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In a growing number of galaxy clusters diffuse extended radio sources have been found. These sources are not directly associated with individual cluster galaxies. The radio emission reveal the presence of cosmic rays and magnetic fields in the intracluster medium (ICM). We classify diffuse cluster radio sources into radio halos, cluster radio shocks (relics), and revived AGN fossil plasma sources. Radio halo sources can be further divided into giant halos, mini-halos, and possible "intermediate" sources. Halos are generally positioned at cluster center and their brightness approximately follows the distribution of the thermal ICM. Cluster radio shocks (relics) are polarized sources mostly found in the cluster's periphery. They trace merger induced shock waves. Revived fossil plasma sources are characterized by their radio steep-spectra and often irregular morphologies. In this review we give an overview of the properties of diffuse cluster radio sources, with an emphasis on recent observational results. We discuss the resulting implications for the underlying physical acceleration processes that operate in the ICM, the role of relativistic fossil plasma, and the properties of ICM shocks and magnetic fields. We also compile an updated list of diffuse cluster radio sources which will be available on-line (http://galaxyclusters.com).

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The discovery of diffuse steep spectrum sources in Abell 2256

Cited by 29 publications

References 28 publications

Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

Recent LOFAR imaging pipeline results

Diffuse Radio Emission from Galaxy Clusters

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