MeerKAT’s view of the bullet cluster 1E 0657-55.8

Sikhosana, Precious; Knowles, Kenda; Hilton, Matt; Moodley, Kavilan; Murgia, M.

doi:10.1093/mnras/stac3370

Cited by 8 publications

(1 citation statement)

References 97 publications

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“…Knowles et al, 2021) including the MeerKAT Galaxy Cluster Legacy Survey (MGCLS; Knowles et al, 2022) which is enabling highly-informative studies of selected cluster systems and the constituent diffuse, non-thermal radio emission (e.g. Riseley et al, 2022a;Giacintucci et al, 2022;Sikhosana et al, 2023;Trehaeven et al, 2023;Riseley et al, 2023). The upgraded Giant Metrewave Radio Telescope (uGMRT; Gupta et al, 2017) is also producing in-depth multi-wavelength studies of galaxy clusters, enabling new detections (e.g.…”

Section: Surveys With Modern Radio Telescopesmentioning

confidence: 99%

Evolutionary Map of the Universe (EMU): A pilot search for diffuse, non-thermal radio emission in galaxy clusters with the Australian SKA Pathfinder

Duchesne,

Botteon,

Koribalski

et al. 2024

Publ. Astron. Soc. Aust.

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Clusters of galaxies have been found to host Mpc-scale diffuse, non-thermal radio emission in the form of central radio halos and peripheral relics. Turbulence and shock-related processes in the intra-cluster medium are generally considered responsible for the emission, though details of these processes are still not clear. The low surface brightness makes detection of the emission a challenge, but with recent surveys with high-sensitivity radio telescopes we are beginning to build large samples of these sources. The Evolutionary Map of the Universe (EMU) is a Southern Sky survey being performed by the Australian SKA Pathfinder (ASKAP) over the next few years and is well-suited to detect and characterise such emission. To assess prospects of the full survey, we have performed a pilot search of diffuse sources in 71 clusters from the Planck Sunyaev–Zeldovich (SZ) cluster catalogue (PSZ2) found in archival ASKAP observations. After re-imaging the archival data and performing both (u, v)-plane and image-plane angular scale filtering, we detect 21 radio halos (12 for the first time, excluding an additional six candidates), 11 relics (in seven clusters, and six for the first time, excluding a further five candidate relics), along with 12 other, unclassified diffuse radio sources. From these detections, we predict the full EMU survey will uncover up to ≈ 254 radio halos and ≈ 85 radio relics in the 858 PSZ2 clusters that will be covered by EMU. The percentage of clusters found to host diffuse emission in this work is similar to the number reported in recent cluster surveys with the LOw Frequency ARray (LOFAR) Two-metre Sky Survey (Botteon, et al. 2022a, A&A, 660, A78), suggesting EMU will complement similar searches being performed in the Northern Sky and provide us with statistically significant samples of halos and relics at the completion of the full survey. This work presents the first step towards large samples of the diffuse radio sources in Southern Sky clusters with ASKAP and eventually the SKA.

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Section: Surveys With Modern Radio Telescopesmentioning

confidence: 99%

Evolutionary Map of the Universe (EMU): A pilot search for diffuse, non-thermal radio emission in galaxy clusters with the Australian SKA Pathfinder

Duchesne,

Botteon,

Koribalski

et al. 2024

Publ. Astron. Soc. Aust.

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DS+: A method for the identification of cluster substructures

Benavides

Biviano

Abadi

2023

A&A

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Context. The study of cluster substructures is important for the determination of the cluster dynamical status, assembly history, and the evolution of cluster galaxies, and it allows us to set constraints on the nature of dark matter and cosmological parameters. Aims. We present and test DS+, a new method for the identification and characterization of group-sized substructures in clusters. Methods. Our new method is based on the projected positions and line-of-sight (l.o.s. hereafter) velocities of cluster galaxies, and it is an improvement and extension of the traditional method of Dressler & Shectman (1988). We tested it on cluster-size cosmological halos extracted from the IllustrisTNG simulations, with virial masses 14 ≲ log(M 200 /M ⊙ ) ≲ 14.6 that contain ∼ 190 galaxies on average. We also present an application of our method on a real data set, the Bullet cluster. Results. DS+ is able to identify ∼ 80% of real group galaxies as members of substructures, and at least 60% of the galaxies assigned to substructures belong to real groups. The physical properties of the real groups are significantly correlated with those of the corresponding detected substructures, but with significant scatter, and they are overestimated on average. Application of the DS+ method to the Bullet cluster confirms the presence and main properties of the high-speed collision and identifies other substructures along the main cluster axis. Conclusions. DS+ proves to be a reliable method for the identification of substructures in clusters. The method is made freely available to the community as a Python code.

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Surface brightness discontinuities in radio halos

Botteon¹,

Markevitch²,

Weeren³

et al. 2023

A&A

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Context. Dynamical motions in the intra-cluster medium (ICM) can imprint distinctive features on X-ray images that map the thermal bremsstrahlung emission from galaxy clusters, such as sharp surface brightness discontinuities due to shocks and cold fronts. The gas dynamics during cluster mergers may also drive large-scale turbulence in the ICM, which in turn generates extended (megaparsec-scale) synchrontron sources known as radio halos. Aims. Surface brightness edges have been found numerous times in the thermal gas of clusters based on X-ray observations. In contrast, edges in radio halos have only been observed in a handful of cases. Our goal is to search for new radio surface brightness discontinuities in the ICM. Methods. We inspected the images of the Bullet Cluster and the other 25 radio halos reported in the MeerKAT Galaxy Cluster Legacy Survey. To aid the identification of surface brightness discontinuities, we applied a gradient-filtering edge-detection method to the radio images. Results. We find that the adopted filtering technique is helpful in identifying surface brightness edges in radio images, allowing us to identify at least one gradient in half of the radio halos studied. For the Bullet Cluster, we find excellent agreement between the locations of the four radio discontinuities detected and the X-ray edges. This similarity informs us that there is substantial interplay between thermal and nonthermal components in galaxy clusters. This interplay is likely due to the frozen-in ICM magnetic field, which mediates the advection of cosmic rays while being dragged by thermal gas flows. Conclusions. We conclude that radio halos are shaped by dynamical motions in the ICM and that they often display surface brightness discontinuities, which appear to be co-located with edges in the thermal gas emission. Our results demonstrate that new and future generations of radio telescopes will provide an approach to efficiently detecting shocks and cold fronts in the ICM that is complementary to X-rays.

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MeerKAT’s view of the bullet cluster 1E 0657-55.8

Cited by 8 publications

References 97 publications

Evolutionary Map of the Universe (EMU): A pilot search for diffuse, non-thermal radio emission in galaxy clusters with the Australian SKA Pathfinder

Evolutionary Map of the Universe (EMU): A pilot search for diffuse, non-thermal radio emission in galaxy clusters with the Australian SKA Pathfinder

DS+: A method for the identification of cluster substructures

Surface brightness discontinuities in radio halos

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