A robust model for flux density calculations of radio halos in galaxy clusters: Halo-FDCA

Boxelaar, J. M.; Weeren, R. J. van; Botteon, A.

doi:10.1016/j.ascom.2021.100464

Cited by 36 publications

(44 citation statements)

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“…We employed the Halo-Flux Density CAlculator 6 (Halo-FDCA; Boxelaar et al 2021) to measure the integrated flux density from the observed radio halos. This code fits the two-dimensional surface brightness profile with a Markov chain Monte Carlo (MCMC) method that estimates the best-fit parameters and associated uncertainties.…”

Section: Radio Halosmentioning

confidence: 99%

“…where the fitted parameters are I 0 , which is the central brightness, and G(r), which is a function that determines the model morphology (i.e., circular, elliptical or skewed; see Boxelaar et al 2021 for more details). As done for the LoTSS-DR1 cluster sample (van Weeren et al 2021), we primarily used a simple circular exponential model to fit the discrete-source-subtracted images that were obtained with a Gaussian uv taper corresponding to 50 kpc at the cluster redshift.…”

Section: Radio Halosmentioning

confidence: 99%

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The Planck clusters in the LOFAR sky. I. LoTSS-DR2: new detections and sample overview

Botteon,

Shimwell,

Cassano

et al. 2022

Preprint

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Context. Relativistic electrons and magnetic fields permeate the intra-cluster medium (ICM) and manifest themselves as diffuse sources of synchrotron emission observable at radio wavelengths, namely radio halos and radio relics. Although there is broad consensus that the formation of these sources is connected to turbulence and shocks in the ICM, the details of the required particle acceleration, the strength and morphology of the magnetic field in the cluster volume, and the influence of other sources of high-energy particles are poorly known. Aims. Sufficiently large samples of radio halos and relics, which would allow us to examine the variation among the source population and pinpoint their commonalities and differences, are still missing. At present, due to the physical properties of the sources and the capabilities of existing facilities, large numbers of these sources are easiest to detect at low radio frequencies, where they shine brightly. Methods. We examined the low-frequency radio emission from all 309 clusters in the second catalog of Planck Sunyaev Zel'dovich detected sources that lie within the 5634 deg 2 covered by the Second Data Release of the LOFAR Two-meter Sky Survey (LoTSS-DR2). We produced LOFAR images at different resolutions, with and without discrete sources subtracted, and created overlays with optical and X-ray images before classifying the diffuse sources in the ICM, guided by a decision tree. Results. Overall, we found 83 clusters that host a radio halo and 26 that host one or more radio relics (including candidates). About half of them are new discoveries. The detection rate of clusters that host a radio halo and one or more relics in our sample is 30 ± 11% and 10 ± 6%, respectively. Extrapolating these numbers, we anticipate that once LoTSS covers the entire northern sky it will provide the detection of 251 ± 92 clusters that host a halo and 83 ± 50 clusters that host at least one relic from Planck clusters alone. All images and results produced in this work are publicly available via the project website.

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Section: Radio Halosmentioning

confidence: 99%

Section: Radio Halosmentioning

confidence: 99%

The Planck clusters in the LOFAR sky. I. LoTSS-DR2: new detections and sample overview

Botteon,

Shimwell,

Cassano

et al. 2022

Preprint

Self Cite

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“…The presented fitting of Equation ( 1) and halo radio flux density estimations were done with a newly developed algorithm 2 . The algorithm is described in detail by Boxelaar et al (2020), and we briefly explain it here. The fitting algorithm is based on fitting methods first presented by Murgia et al (2009).…”

Section: Measuring Radio Halo Propertiesmentioning

confidence: 99%

Diffuse radio emission from galaxy clusters in the LOFAR Two-metre Sky Survey Deep Fields

Osinga

Weeren

Boxelaar

et al. 2021

A&A

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Low-frequency radio observations are revealing an increasing number of diffuse synchrotron sources from galaxy clusters, primarily in the form of radio halos or radio relics. The existence of this diffuse synchrotron emission indicates the presence of relativistic particles and magnetic fields. It is still an open question as to exactly what mechanisms are responsible for the population of relativistic electrons driving this synchrotron emission. The LOFAR Two-metre Sky Survey Deep Fields offer a unique view of this problem. Reaching noise levels below 30 μJy beam−1, these are the deepest images made at the low frequency of 144 MHz. This paper presents a search for diffuse emission in galaxy clusters in the first data release of the LOFAR Deep Fields. We detect a new high-redshift radio halo with a flux density of 8.9 ± 1.0 mJy and corresponding luminosity of P144MHz = (3.6 ± 0.6) × 1025 W Hz−1 in an X-ray detected cluster at z = 0.77 with a mass estimate of M500 = 3.3−1.7+1.1 × 1014 M⊙. Deep upper limits are placed on clusters with non-detections. We compare the results to the correlation between halo luminosity and cluster mass derived for radio halos found in the literature. This study is one of a few to find diffuse emission in low mass (M500 < 5 × 1014 M⊙) systems and shows that deep low-frequency observations of galaxy clusters are fundamental for opening up a new part of parameter space in the study of non-thermal phenomena in galaxy clusters.

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“…Assuming 𝛼 = −1.4, frequency-dependent model radio haloes are simulated in each 216-MHz snapshot independently following the standard circular exponential profile (e.g. Orrú et al 2007;Murgia et al 2009;Bonafede et al 2009;Boxelaar et al 2021),…”

Section: Simulating a Giant Radio Halomentioning

confidence: 99%

“…Measurements with a low SNR can also under-estimate integrated flux densities which can be mitigated somewhat by fitting a model to the surface brightness profile (e.g. Bonafede et al 2017;Boxelaar et al 2021). In this work the flux density limits are obtained from the input model rather than measured in the resultant image avoiding this issue, and limits are derived from the 150-MHz scaling relations where USSRH are not under-luminous (e.g.…”

Section: Why Do We Not Detect a Giant Radio Halo?mentioning

confidence: 99%

The merging galaxy cluster Abell 3266 at low radio frequencies

Duchesne,

Johnston-Hollitt,

Riseley

et al. 2022

Preprint

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We present new low-frequency (𝜈 = 88-216 MHz) observations of the complex merging galaxy cluster Abell 3266. These new observations are taken with the Murchison Widefield Array (MWA) in its Phase II 'extended', long-baseline configuration, offering the highest-resolution low-frequency view of the cluster to date. We report on the detection of four steep spectrum (𝛼 −1 for 𝑆 𝜈 ∝ 𝜈 𝛼 ) extended radio sources within the cluster. We confirm the detection of a ∼ 570 kpc radio relic to the south of the cluster, and a possible bridge of emission connecting the relic to the cluster core. We also detect two new ultrasteep-spectrum (𝛼 −1.7) fossil plasma sources to the north and west of the cluster centre without associated compact radio emission. A previously detected radio galaxy in the cluster is also found to have a spectrally steepening tail with steep-spectrum components highlighted by the MWA. We do not detect a giant radio halo in the cluster. After simulating a range of radio haloes at 216 MHz we place upper limits on the radio luminosity corresponding to ∼ 7.2 × 10 24 W Hz −1 at 150 MHz assuming the expected 500 kpc radius, up to a factor 5 lower than expected from scaling relations. Why a giant radio halo is undetected in Abell 3266 is unclear -the timeline of the merger and overall mass of the system as determined by optical and X-ray studies suggest the foundation for a hosting system.

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A robust model for flux density calculations of radio halos in galaxy clusters: Halo-FDCA

Cited by 36 publications

References 50 publications

The Planck clusters in the LOFAR sky. I. LoTSS-DR2: new detections and sample overview

The Planck clusters in the LOFAR sky. I. LoTSS-DR2: new detections and sample overview

Diffuse radio emission from galaxy clusters in the LOFAR Two-metre Sky Survey Deep Fields

The merging galaxy cluster Abell 3266 at low radio frequencies

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