We have studied radio haloes and relics in nine merging galaxy clusters using the Murchison Widefield Array (MWA). The images used for this study were obtained from the GaLactic and Extragalactic All-sky MWA (GLEAM) Survey which was carried out at 5 frequencies, viz. 88, 118, 154, 188 and 215 MHz. We detect diffuse radio emission in 8 of these clusters. We have estimated the spectra of haloes and relics in these clusters over the frequency range 80-1400 MHz; the first such attempt to estimate their spectra at low frequencies. The spectra follow a power law with a mean value of α=−1.13±0.21 for haloes and α=−1.2±0.19 for relics where, S∝να. We reclassify two of the cluster sources as radio galaxies. The low frequency spectra are thus an independent means of confirming the nature of cluster sources. Five of the nine clusters host radio haloes. For the remaining four clusters, we place upper limits on the radio powers of possible haloes in them. These upper limits are a factor of 2-20 below those expected from the LX−P1.4 relation. These limits are the lowest ever obtained and the implications of these limits to the hadronic model of halo emission are discussed.
@article{arxiv.1701.06742,
title = {A study of halo and relic radio emission in merging clusters using the Murchison Widefield Array},
author = {L. T. George and K. S. Dwarakanath and M. Johnston-Hollitt and H. T. Intema and N. Hurley-Walker and M. E. Bell and J. R. Callingham and Bi-Qing For and B. Gaensler and P. J. Hancock and L. Hindson and A. D. Kapińska and E. Lenc and B. McKinley and J. Morgan and A. Offringa and P. Procopio and L. Staveley-Smith and R. B. Wayth and Chen Wu and Q. Zheng},
journal= {arXiv preprint arXiv:1701.06742},
year = {2017}
}