Browsing by Author "Durret, Florence"

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    Giant Ringlike Radio Structures Around Galaxy Cluster Abell 3376
    (2007-11-09) Bagchi, Joydeep; Durret, Florence; Paul, Surajit; et al.
    In the current paradigm of cold dark matter cosmology, large-scale structures are assembling through hierarchical clustering of matter. In this process, an important role is played by megaparsec (Mpc)-scale cosmic shock waves, arising in gravity-driven supersonic flows of intergalactic matter onto dark matter-dominated collapsing structures such as pancakes, filaments and clusters of galaxies. Here we report Very Large Array telescope observations of giant (∼ 2 Mpc ×1.6 Mpc), ring-shaped non-thermal radio emitting structures, found at the outskirts of the rich cluster of galaxies Abell 3376. These structures may trace the elusive shock waves of cosmological large scale matter flows, which are energetic enough to power them. These radio sources may also be the acceleration sites where magnetic shocks are possibly boosting 1cosmic-ray particles with energies of up to 1018 to 1019 electron volts.
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    High & ultra-high energy cosmic ray acceleration in structure-formation shocks in Abell 3376 galaxy cluster
    (2005-09-01) Bagchi, Joydeep; Paul, Surajit; Durret, Florence; et al.
    We describemultiwavelength optical, X-ray and radio evidences of energeticmergers in southern galaxy cluster Abell 3376 (A3376, redshift z=0.046, X-ray luminosity "#$&'($' ( ). Here we report the rare discovery of gigantic, Mpc-scale non-thermal radio structures (‘radio-arcs’), shaped like a pair of bow-shock fronts on the merger axis. We argue for the shock acceleration origin of the radio emission and discuss the possibilty of acceleration of very high energy cosmic ray particles in this and similar clusters