A study of halo and relic radio emission in merging clusters using the Murchison Widefield Array

L. T. George, K. S. S. Dwarakanath, M. Johnston-Hollitt, H.T. Intema, N. Hurley-Walker, M. E. Bell, J. R. Callingham, B. -Q. For, B. Gaensler, P. J. Hancock, L. Hindson, A. D. Kapinska, E. Lenc, B. Mckinley, J. Morgan, A. Offringa, P. Procopio, L. Staveley-Smith, R. B. Wayth, C. Wu & 1 others Q. Zheng

Research output: Contribution to journalArticle

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 languageEnglish
Pages (from-to)936-949
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Volume467
Issue number1
DOIs
Publication statusPublished - 11 May 2017

Cite this

George, L. T., Dwarakanath, K. S. S., Johnston-Hollitt, M., Intema, H. T., Hurley-Walker, N., Bell, M. E., ... Zheng, Q. (2017). A study of halo and relic radio emission in merging clusters using the Murchison Widefield Array. Monthly Notices of the Royal Astronomical Society, 467(1), 936-949. https://doi.org/10.1093/mnras/stx155
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. / A study of halo and relic radio emission in merging clusters using the Murchison Widefield Array. In: Monthly Notices of the Royal Astronomical Society. 2017 ; Vol. 467, No. 1. pp. 936-949.
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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. {\circledC} 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society",
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George, LT, Dwarakanath, KSS, Johnston-Hollitt, M, Intema, HT, Hurley-Walker, N, Bell, ME, Callingham, JR, For, B-Q, Gaensler, B, Hancock, PJ, Hindson, L, Kapinska, AD, Lenc, E, Mckinley, B, Morgan, J, Offringa, A, Procopio, P, Staveley-Smith, L, Wayth, RB, Wu, C & Zheng, Q 2017, 'A study of halo and relic radio emission in merging clusters using the Murchison Widefield Array' Monthly Notices of the Royal Astronomical Society, vol. 467, no. 1, pp. 936-949. https://doi.org/10.1093/mnras/stx155

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 journalArticle

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 -

George LT, Dwarakanath KSS, Johnston-Hollitt M, Intema HT, Hurley-Walker N, Bell ME et al. A study of halo and relic radio emission in merging clusters using the Murchison Widefield Array. Monthly Notices of the Royal Astronomical Society. 2017 May 11;467(1):936-949. https://doi.org/10.1093/mnras/stx155