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FältnamnIndikatorerMetadata
00006867naa a2201477 4500
001oai:research.chalmers.se:7e16bb35-b32c-43db-a46c-a0fa3d55c265
003SwePub
008171007s2012 | |||||||||||000 ||eng|
024a https://doi.org/10.1051/0004-6361/2012191542 DOI
024a https://research.chalmers.se/publication/1632892 URI
040 a (SwePub)cth
041 a engb eng
042 9 SwePub
072 7a art2 swepub-publicationtype
072 7a ref2 swepub-contenttype
100a van Weeren, R. J.4 aut
2451 0a First LOFAR observations at very low frequencies of cluster-scale non-thermal emission: the case of Abell 2256
264 c 2012-06-25
264 1b EDP Sciences,c 2012
338 a electronic2 rdacarrier
520 a Abell 2256 is one of the best known examples of a galaxy cluster hosting large-scale diffuse radio emission that is unrelated to individual galaxies. It contains both a giant radio halo and a relic, as well as a number of head-tail sources and smaller diffuse steep-spectrum radio sources. The origin of radio halos and relics is still being debated, but over the last years it has become clear that the presence of these radio sources is closely related to galaxy cluster merger events. Here we present the results from the first LOFAR low band antenna (LBA) observations of Abell 2256 between 18 and 67 MHz. To our knowledge, the image presented in this paper at 63 MHz is the deepest ever obtained at frequencies below 100 MHz in general. Both the radio halo and the giant relic are detected in the image at 63 MHz, and the diffuse radio emission remains visible at frequencies as low as 20 MHz. The observations confirm the presence of a previously claimed ultra-steep spectrum source to the west of the cluster center with a spectral index of -2.3 +/- 0.4 between 63 and 153 MHz. The steep spectrum suggests that this source is an old part of a head-tail radio source in the cluster. For the radio relic we find an integrated spectral index of -0.81 +/- 0.03, after removing the flux contribution from the other sources. This is relatively flat which could indicate that the efficiency of particle acceleration at the shock substantially changed in the last similar to 0.1 Gyr due to an increase of the shock Mach number. In an alternative scenario, particles are re-accelerated by some mechanism in the downstream region of the shock, resulting in the relatively flat integrated radio spectrum. In the radio halo region we find indications of low-frequency spectral steepening which may suggest that relativistic particles are accelerated in a rather inhomogeneous turbulent region.
650 7a NATURVETENSKAPx Fysikx Astronomi, astrofysik och kosmologi0 (SwePub)103052 hsv//swe
650 7a NATURAL SCIENCESx Physical Sciencesx Astronomy, Astrophysics and Cosmology0 (SwePub)103052 hsv//eng
653 a galaxies: clusters: individual: Abell
653 a deep
653 a astrophysical shocks
653 a coma cluster
653 a shock acceleration
653 a sky survey
653 a x-ray-emission
653 a radio continuum: general
653 a 1.4 ghz
653 a particle-acceleration
653 a magnetic-fields
653 a telescopes
653 a extended radio-emission
653 a merging galaxy cluster
700a Rottgering, H.4 aut
700a Rafferty, D.4 aut
700a Pizzo, R.4 aut
700a Bonafede, A.4 aut
700a Brüggen, M.4 aut
700a Brunetti, G.4 aut
700a Ferrari, C.4 aut
700a Orru, E.4 aut
700a Heald, G.4 aut
700a McKean, J. P.4 aut
700a Tasse, C.4 aut
700a De Gasperin, F.4 aut
700a Birzan, L.4 aut
700a van Zwieten, J. E.4 aut
700a van der Tol, S.4 aut
700a Shulevski, A.4 aut
700a Jackson, N.4 aut
700a Offringa, A. R.4 aut
700a Conway, John,d 1963u Chalmers tekniska högskola,Chalmers University of Technology4 aut0 (Swepub:cth)jconway
700a Intema, H. T.4 aut
700a Clarke, T. E.4 aut
700a van Bemmel, I.4 aut
700a Miley, G. K.4 aut
700a White, G. J.4 aut
700a Hoeft, M.4 aut
700a Cassano, R.4 aut
700a Macario, G.4 aut
700a Morganti, R.4 aut
700a Wise, M. W.4 aut
700a Horellou, Cathy,d 1967u Chalmers tekniska högskola,Chalmers University of Technology4 aut0 (Swepub:cth)horellou
700a Valentijn, E. A.4 aut
700a Wucknitz, O.4 aut
700a Kuijken, K.4 aut
700a Ensslin, T. A.4 aut
700a Anderson, J.4 aut
700a Asgekar, A.4 aut
700a Avruch, I. M.4 aut
700a Beck, R.4 aut
700a Bell, M. E.4 aut
700a Bell, M. R.4 aut
700a Bentum, M. J.4 aut
700a Bernardi, G.4 aut
700a Best, P.4 aut
700a Boonstra, A. J.4 aut
700a Brentjens, M.4 aut
700a van de Brink, R. H.4 aut
700a Broderick, J.4 aut
700a Brouw, W. N.4 aut
700a Butcher, H. R.4 aut
700a van Cappellen, W.4 aut
700a Ciardi, B.4 aut
700a Eisloffel, J.4 aut
700a Falcke, H.4 aut
700a Fender, R.4 aut
700a Garrett, M. A.4 aut
700a Gerbers, M.4 aut
700a Gunst, A.4 aut
700a van Haarlem, M. P.4 aut
700a Hamaker, J. P.4 aut
700a Hassall, T.4 aut
700a Hessels, J. W. T.4 aut
700a Koopmans, L. V. E.4 aut
700a Kuper, G.4 aut
700a van Leeuwen, J.4 aut
700a Maat, P.4 aut
700a Millenaar, R.4 aut
700a Munk, H.4 aut
700a Nijboer, R.4 aut
700a Noordam, J. E.4 aut
700a Pandey, V. N.4 aut
700a Pandey-Pommier, M.4 aut
700a Polatidis, A.4 aut
700a Reich, W.4 aut
700a Scaife, A. M. M.4 aut
700a Schoenmakers, A.4 aut
700a Sluman, J.4 aut
700a Stappers, B. W.4 aut
700a Steinmetz, M.4 aut
700a Swinbank, J.4 aut
700a Tagger, M.4 aut
700a Tang, Y.4 aut
700a Vermeulen, R.4 aut
700a de Vos, M.4 aut
710a Chalmers tekniska högskola4 org
773t Astronomy and Astrophysicsd : EDP Sciencesg 543, s. Article Number: A43 -q 543<Article Number: A43 -x 0004-6361x 1432-0746
856u http://publications.lib.chalmers.se/records/fulltext/local_163289.pdfx primaryx freey FULLTEXT
856u https://www.aanda.org/articles/aa/pdf/2012/07/aa19154-12.pdf
8564 8u https://doi.org/10.1051/0004-6361/201219154
8564 8u https://research.chalmers.se/publication/163289

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