Abstract
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 five frequencies, viz. 88, 118, 154, 188 and 215 MHz. We detect diffuse radio emission in eight 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 alpha = -1.13 +/- 0.21 for haloes and alpha = -1.2 +/- 0.19 for relics, where S alpha v(alpha). 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 L-X-P-1.4 relation. These limits are the lowest ever obtained and the implications of these limits to the hadronic model of halo emission are discussed. © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
| Original language | English |
|---|---|
| Pages (from-to) | 936-949 |
| Number of pages | 14 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 467 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 11 May 2017 |
Cite this
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A study of halo and relic radio emission in merging clusters using the Murchison Widefield Array. / George, L. T.; Dwarakanath, K. S. S.; Johnston-Hollitt, M.; Intema, H.T.; Hurley-Walker, N.; Bell, M. E.; Callingham, J. R. ; For, B. -Q.; Gaensler, B. ; Hancock, P. J.; Hindson, L.; Kapinska, A. D.; Lenc, E.; Mckinley, B.; Morgan, J.; Offringa, A.; Procopio, P.; Staveley-Smith, L.; Wayth, R. B. ; Wu, C.; Zheng, Q.
In: Monthly Notices of the Royal Astronomical Society, Vol. 467, No. 1, 11.05.2017, p. 936-949.Research output: Contribution to journal › Article
TY - JOUR
T1 - A study of halo and relic radio emission in merging clusters using the Murchison Widefield Array
AU - George, L. T.
AU - Dwarakanath, K. S. S.
AU - Johnston-Hollitt, M.
AU - Intema, H.T.
AU - Hurley-Walker, N.
AU - Bell, M. E.
AU - Callingham, J. R.
AU - For, B. -Q.
AU - Gaensler, B.
AU - Hancock, P. J.
AU - Hindson, L.
AU - Kapinska, A. D.
AU - Lenc, E.
AU - Mckinley, B.
AU - Morgan, J.
AU - Offringa, A.
AU - Procopio, P.
AU - Staveley-Smith, L.
AU - Wayth, R. B.
AU - Wu, C.
AU - Zheng, Q.
PY - 2017/5/11
Y1 - 2017/5/11
N2 - 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 five frequencies, viz. 88, 118, 154, 188 and 215 MHz. We detect diffuse radio emission in eight 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 alpha = -1.13 +/- 0.21 for haloes and alpha = -1.2 +/- 0.19 for relics, where S alpha v(alpha). 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 L-X-P-1.4 relation. These limits are the lowest ever obtained and the implications of these limits to the hadronic model of halo emission are discussed. © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
AB - 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 five frequencies, viz. 88, 118, 154, 188 and 215 MHz. We detect diffuse radio emission in eight 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 alpha = -1.13 +/- 0.21 for haloes and alpha = -1.2 +/- 0.19 for relics, where S alpha v(alpha). 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 L-X-P-1.4 relation. These limits are the lowest ever obtained and the implications of these limits to the hadronic model of halo emission are discussed. © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
KW - radiation mechanisms: non-thermal
KW - techniques: interferometric
KW - galaxies:clusters: general
KW - galaxies: clusters: intracluster medium
KW - radio continuum: general
KW - X-rays:galaxies: clusters
KW - RAY BRIGHTEST CLUSTERS
KW - X-RAY
KW - GALAXY CLUSTERS
KW - COSMIC-RAYS
KW - GAMMA-RAY
KW - CHANDRA OBSERVATION
KW - SHOCK ACCELERATION
KW - INTERNAL DYNAMICS
KW - MAGNETIC-FIELDS
KW - COMA CLUSTER
U2 - 10.1093/mnras/stx155
DO - 10.1093/mnras/stx155
M3 - Article
VL - 467
SP - 936
EP - 949
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 1
ER -