Low frequency follow up of radio haloes and relics in the GMRT Radio Halo Cluster Survey

Venturi, T.; Giacintucci, S.; Dallacasa, D.; Cassano, R.; Brunetti, G.; Macario, G.; Athreya, R.

doi:10.1051/0004-6361/201219872

Cited by 69 publications

(101 citation statements)

References 82 publications

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“…Comparison of the spectral index and Mach number of various radio relics taken from the literature. The Mach number is not presented for relics observed by Venturi et al (2013) so we derive a lower limit using the average spectral index for the relics and highlight these Mach numbers with an . An annulus, marked B shows the centre of the cluster, defined by the peak in X-ray emission, and the size of the annulus corresponds to the expected radio halo size of 430 and 500 kpc.…”

Section: Radio Bridgementioning

confidence: 99%

The First Murchison Widefield Array low-frequency radio observations of cluster scale non-thermal emission: the case of Abell 3667

Hindson¹,

Johnston‐Hollitt²,

Hurley‐Walker³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present the first Murchison Widefield Array observations of the well-known cluster of galaxies Abell 3667 (A3667) between 105 and 241 MHz. A3667 is one of the best known examples of a galaxy cluster hosting a double radio relic and has been reported to contain a faint radio halo and bridge. The origin of radio haloes, relics and bridges is still unclear, however galaxy cluster merger seems to be an important factor. We clearly detect the north-west (NW) and south-east radio relics in A3667 and find an integrated flux density at 149 MHz of 28.1 ± 1.7 and 2.4 ± 0.1 Jy, respectively, with an average spectral index, between 120 and 1400 MHz, of −0.9 ± 0.1 for both relics. We find evidence of a spatial variation in the spectral index across the NW relic steepening towards the centre of the cluster, which indicates an ageing electron population. These properties are consistent with higher frequency observations. We detect emission that could be associated with a radio halo and bridge. However, due to the presence of poorly sampled large-scale Galactic emission and blended point sources we are unable to verify the exact nature of these features.

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Section: Radio Bridgementioning

confidence: 99%

The First Murchison Widefield Array low-frequency radio observations of cluster scale non-thermal emission: the case of Abell 3667

Hindson¹,

Johnston‐Hollitt²,

Hurley‐Walker³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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“…The cluster has since been observed at radio frequencies of 1.4 GHz by Govoni et al (2001) and at 325MHz by Orrú et al (2007) and Venturi et al (2013). Herein these observations shall be referred to as "G01," "O07," and "V13" respectively.…”

Section: Previous Radio Studies Of Abell 2744mentioning

confidence: 99%

VLA Radio Observations of the HST Frontier Fields Cluster Abell 2744: The Discovery of New Radio Relics

Pearce

Weeren

Andrade-Santos

et al. 2017

ApJ

117

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Cluster mergers leave distinct signatures in the intracluster medium (ICM) in the form of shocks and diffuse cluster radio sources that provide evidence for the acceleration of relativistic particles. However, the physics of particle acceleration in the ICM is still not fully understood. Here we present new 1-4 GHz Jansky Very Large Array (VLA) and archival Chandra observations of the HST Frontier Fields Cluster Abell2744. In our new VLA images, we detect the previously known ∼2.1Mpc radio halo and ∼1.5Mpc radio relic. We carry out a radio spectral analysis from which we determine the relic's injection spectral index to be a = - 1.12 0. 0.31 under the assumption of diffusive shock acceleration. We also find evidence for spectral steepening in the post-shock region. We do not find evidence for a significant correlation between the radio halo's spectral index and ICM temperature. In addition, we observe three new polarized diffuse sources and determine two of these to be newly discovered giant radio relics. These two relics are located in the southeastern and northwestern outskirts of the cluster. The corresponding integrated spectral indices measure −1.81±0.26 and −0.63±0.21 for the SE and NW relics, respectively. From an X-ray surface brightness profile we also detect a possible density jump of = -+ R 1.39 0.22 0.34 co-located with the newly discovered SE relic. This density jump would correspond to a shock front Mach number of  = -+ 1.26 0.15 0.25 .

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“…(1) Venturi et al (2007); (2) Venturi et al (2008); (3) Giovannini & Feretti (2000); (4) Bonafede et al (2009); (5) Govoni et al (2009); (6) Kale et al (2013); (7) Kale et al (2015); (8) van Weeren et al (2011); (9) Giacintucci et al (2014b); (10) van Weeren et al (2013); (11) Brunetti et al (2008); (12) Bacchi et al (2003); (13) Giacintucci et al (2011a); (14) Govoni et al (2001); (15) Giacintucci et al (2014a); (16) Giacintucci et al (2009); (17) Giovannini et al (2006); (18) Giacintucci et al (2011b); (19) Murgia et al (2009); (20) Vacca et al (2011); (21) Venturi et al 2013;(22) Giacintucci et al (2013); (23) Feretti et al (2001); (24) …”

Section: The Low-z Sample and The Nvss Data Analysisunclassified

Occurrence of radio halos in galaxy clusters

Cuciti

Cassano

Brunetti

et al. 2015

A&A

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139

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Context. Giant radio halos (RH) are diffuse Mpc-scale synchrotron sources detected in some massive and merging galaxy clusters. An unbiased study of the statistical properties of RHs is crucial to constraining their origin and evolution. Aims. We investigate the occurrence of RHs and its dependence on the cluster mass in a Sunyaev-Zel'dovich (SZ)-selected sample of galaxy clusters, which is nearly a mass-selected sample. Moreover, we analyse the connection between RHs and merging clusters. Methods. We selected from the Planck SZ catalogue clusters with M ≥ 6 × 10 14 M at z = 0.08−0.33 and we searched for the presence of RHs using the NVSS for z < 0.2 and the GMRT RH survey (GRHS) and its extension (EGRHS) for 0.2 < z < 0.33. We used archival Chandra X-ray data to derive information on the dynamical status of the clusters. Results. We confirm that RH clusters are merging systems while the majority of clusters without RH are relaxed, thus supporting the idea that mergers play a fundamental role in the generation of RHs. We find evidence for an increase in the fraction of clusters with RHs with the cluster mass and this is in line with expectations derived on the basis of the turbulence re-acceleration scenario. Finally, we discuss the effect of the incompleteness of our sample on this result.

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Low frequency follow up of radio haloes and relics in the GMRT Radio Halo Cluster Survey

Cited by 69 publications

References 82 publications

The First Murchison Widefield Array low-frequency radio observations of cluster scale non-thermal emission: the case of Abell 3667

The First Murchison Widefield Array low-frequency radio observations of cluster scale non-thermal emission: the case of Abell 3667

VLA Radio Observations of the HST Frontier Fields Cluster Abell 2744: The Discovery of New Radio Relics

Occurrence of radio halos in galaxy clusters

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