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Title: Mapping the particle acceleration in the cool core of the galaxy cluster RX J1720.1+2638

We present new deep, high-resolution radio images of the diffuse minihalo in the cool core of the galaxy cluster RX J1720.1+2638. The images have been obtained with the Giant Metrewave Radio Telescope at 317, 617, and 1280 MHz and with the Very Large Array at 1.5, 4.9, and 8.4 GHz, with angular resolutions ranging from 1'' to 10''. This represents the best radio spectral and imaging data set for any minihalo. Most of the radio flux of the minihalo arises from a bright central component with a maximum radius of ∼80 kpc. A fainter tail of emission extends out from the central component to form a spiral-shaped structure with a length of ∼230 kpc, seen at frequencies 1.5 GHz and below. We find indication of a possible steepening of the total radio spectrum of the minihalo at high frequencies. Furthermore, a spectral index image shows that the spectrum of the diffuse emission steepens with increasing distance along the tail. A striking spatial correlation is observed between the minihalo emission and two cold fronts visible in the Chandra X-ray image of this cool core. These cold fronts confine the minihalo, as also seen in numerical simulations of minihalo formation by sloshing-inducedmore » turbulence. All these observations favor the hypothesis that the radio-emitting electrons in cluster cool cores are produced by turbulent re-acceleration.« less
Authors:
 [1] ;  [2] ; ;  [3] ;  [4] ; ;  [5]
  1. Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
  2. Joint Space-Science Institute, University of Maryland, College Park, MD, 20742-2421 (United States)
  3. INAF—Istituto di Radioastronomia, Via Gobetti 101, I-40129 Bologna (Italy)
  4. Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  5. Dipartimento di Fisica, Universitá di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Rome (Italy)
Publication Date:
OSTI Identifier:
22370301
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 795; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPUTERIZED SIMULATION; CORRELATIONS; DISTANCE; ELECTRONS; EMISSION; GALAXY CLUSTERS; HYPOTHESIS; IMAGES; RADIO TELESCOPES; RESOLUTION; SPECTRA; TURBULENCE; X RADIATION; X-RAY GALAXIES