TY - JOUR
T1 - The widest frequency radio relic spectra
T2 - Observations from 150 MHz to 30 GHz
AU - Stroe, Andra
AU - Shimwell, Timothy
AU - Rumsey, Clare
AU - Van Weeren, Reinout
AU - Kierdorf, Maja
AU - Donnert, Julius
AU - Jones, Thomas W.
AU - Röttgering, Huub J.A.
AU - Hoeft, Matthias
AU - Rodríguez-Gonzálvez, Carmen
AU - Harwood, Jeremy J.
AU - Saunders, Richard D.E.
N1 - Publisher Copyright:
© 2015 The Authors.
PY - 2016/1/21
Y1 - 2016/1/21
N2 - Radio relics are patches of diffuse synchrotron radio emission that trace shock waves. Relics are thought to form when intracluster medium electrons are accelerated by cluster mergerinduced shock waves through the diffusive shock acceleration mechanism. In this paper, we present observations spanning 150 MHz to 30 GHz of the 'Sausage' and 'Toothbrush' relics from the Giant Metrewave and Westerbork telescopes, the Karl G. Jansky Very Large Array, the Effelsberg telescope, the Arcminute Microkelvin Imager and Combined Array for Research in Millimeter-wave Astronomy.We detect both relics at 30 GHz, where the previous highest frequency detection was at 16 GHz. The integrated radio spectra of both sources clearly steepen above 2 GHz, at the ≳6σ significance level, supporting the spectral steepening previously found in the 'Sausage' and the Abell 2256 relic. Our results challenge the widely adopted simple formation mechanism of radio relics and suggest more complicated models have to be developed that, for example, involve re-acceleration of aged seed electrons.
AB - Radio relics are patches of diffuse synchrotron radio emission that trace shock waves. Relics are thought to form when intracluster medium electrons are accelerated by cluster mergerinduced shock waves through the diffusive shock acceleration mechanism. In this paper, we present observations spanning 150 MHz to 30 GHz of the 'Sausage' and 'Toothbrush' relics from the Giant Metrewave and Westerbork telescopes, the Karl G. Jansky Very Large Array, the Effelsberg telescope, the Arcminute Microkelvin Imager and Combined Array for Research in Millimeter-wave Astronomy.We detect both relics at 30 GHz, where the previous highest frequency detection was at 16 GHz. The integrated radio spectra of both sources clearly steepen above 2 GHz, at the ≳6σ significance level, supporting the spectral steepening previously found in the 'Sausage' and the Abell 2256 relic. Our results challenge the widely adopted simple formation mechanism of radio relics and suggest more complicated models have to be developed that, for example, involve re-acceleration of aged seed electrons.
KW - Acceleration of particles
KW - Galaxies: clusters: individual: 1RXS j0603.3+4214
KW - Galaxies: clusters: individual: CIZA j2242.8+5301
KW - Radiation mechanisms: non-thermal
KW - Radio continuum: general
KW - Shock waves
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U2 - 10.1093/mnras/stv2472
DO - 10.1093/mnras/stv2472
M3 - Article
AN - SCOPUS:84959080022
SN - 0035-8711
VL - 455
SP - 2402
EP - 2416
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -