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Title: Deep VLA Observations of the Cluster 1RXS J0603.3+4214 in the Frequency Range of 1–2 GHz

Here, we report L-band VLA observations of 1RXS J0603.3+4214, a cluster that hosts a bright radio relic, known as the Toothbrush, and an elongated giant radio halo. These new observations allow us to study the surface brightness distribution down to 1 arcsec resolution with very high sensitivity. Our images provide an unprecedented detailed view of the Toothbrush, revealing enigmatic filamentary structures. To study the spectral index distribution, we complement our analysis with published LOFAR and GMRT observations. The bright "brush" of the Toothbrush shows a prominent narrow ridge to its north with a sharp outer edge. The spectral index at the ridge is in the range –0.70 ≤ α ≤ –0.80. We suggest that the ridge is caused by projection along the line of sight. With a simple toy model for the smallest region of the ridge, we conclude that the magnetic field is below 5 μG and varies significantly across the shock front. Our model indicates that the actual Mach number is higher than that obtained from the injection index and agrees well with the one derived from the overall spectrum, namely $${ \mathcal M }={3.78}_{-0.2}^{+0.3}$$. The radio halo shows an average spectral index of α = –1.16 ± 0.05 and a slight gradient from north to south. The southernmost part of the halo is steeper and possibly related to a shock front. Excluding the southernmost part, the halo morphology agrees very well with the X-ray morphology. A power-law correlation is found between the radio and X-ray surface brightness.
Authors:
ORCiD logo [1] ;  [1] ;  [2] ;  [3] ;  [4] ; ORCiD logo [2] ;  [5] ; ORCiD logo [6] ; ORCiD logo [2] ; ORCiD logo [7] ; ORCiD logo [4] ;  [2] ;  [2] ;  [8]
  1. Thuringer Landessternwarte, Tautenburg (Germany)
  2. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
  3. Univ. of Minnesota, Minneapolis, MN (United States)
  4. Leiden Univ., Leiden (The Netherlands)
  5. Univ. Hamburg, Hamburg (Germany)
  6. The Open Univ., Milton Keynes (United Kingdom)
  7. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  8. Yonsei Univ., Seoul (Korea); Univ. of California, Davis, CA (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-748250
Journal ID: ISSN 1538-4357
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 852; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; acceleration of particles; galaxies: clusters: individual (1RXS J0603.3 + 4214); galaxies: clusters: intracluster medium; large-scale structure of universe; magnetic fields; radiation mechanisms: non-thermal
OSTI Identifier:
1438766