The MeerKAT Massive Distant Clusters Survey: detection of diffuse radio emission in galaxy clusters at $z>1$

Abstract

Diffuse, low surface-brightness radio emission in merging galaxy clusters provides insights into cosmic structure formation, the growth of magnetic fields, and turbulence. This paper reports a search for diffuse radio emission in a pilot sample of six high-redshift ($1.01<z<1.31$) galaxy clusters from the MeerKAT Massive Distant Cluster Survey (MMDCS). These six clusters are selected as the most massive $(M_{500c}=6.7-8.5\times 10^{14}{\mathrm{M}}_{\odot })$ systems based on their Sunyaev-Zel'dovich mass from the full MMDCS sample of 30 ACT DR5 clusters, and were observed first to explore the high-mass, high-redshift regime. Diffuse radio emission is confidently detected in four clusters and tentatively identified in two, with $k$-corrected radio powers scaled to 1.4 GHz ranging from $(0.46\pm 0.16)$ to $(4.51\pm 1.68)\times 10^{24}\mathrm{WH}{\mathrm{z}}^{-1}$ and linear sizes between 0.47 and 1.08 Mpc. Combining $Chandra$ X-ray data with MeerKAT radio data, we find that 80$\%$ of clusters with X-ray observations exhibit disturbed morphologies indicative of mergers. These $z>1$ galaxy clusters scatter around the established radio power-mass scaling relation observed at lower redshifts, supporting turbulent re-acceleration models in high-redshift mergers. However, their radio spectra are predicted to steepen ($\alpha <-1.5$) due to enhanced inverse Compton losses in the cosmic microwave background, rendering them under-luminous at 1.4 GHz and placing them below the correlation. Our results demonstrate that merger-driven turbulence can sustain radio halos even at $z>1$ while highlighting MeerKAT's unique ability to probe non-thermal processes in the early universe.

19 pages, 16 figures, 4 tables. Accepted for publication in MNRAS on the 8th of August 2025

References in corpus (33)

• CASA, the Common Astronomy Software Applications for Radio Astronomy
• WSClean: an implementation of a fast, generic wide-field imager for radio astronomy
• Constraints on the Self-Interaction Cross-Section of Dark Matter from Numerical Simulations of the Merging Galaxy Cluster 1E 0657-5
• Shocks and cold fronts in galaxy clusters
• Diffuse Radio Emission from Galaxy Clusters
• The Last of FIRST: The Final Catalog and Source Identifications
• On the connection between giant radio halos and cluster mergers
• Galaxy clusters discovered with a Sunyaev-Zel'dovich effect survey
• Revisiting the radio interferometer measurement equation. I. A full-sky Jones formalism
• Science With The Australian Square Kilometre Array Pathfinder
• Radio signature of cosmological structure formation shocks
• Radio interferometric gain calibration as a complex optimization problem
• The Case for Electron Re-Acceleration at Galaxy Cluster Shocks
• The impact of mergers on relaxed X-ray clusters - II. Effects on global X-ray and SZ properties and their scaling relations
• Non-linear Kalman filters for calibration in radio interferometry
• The 1.28 GHz MeerKAT DEEP2 Image
• Revisiting the radio interferometer measurement equation. II. Calibration and direction-dependent effects
• Particle acceleration mechanisms
• Radio halos in a mass-selected sample of 75 galaxy clusters. II. Statistical analysis
• Fast magnetic field amplification in distant galaxyclusters
• Morphology parameters: substructure identification in X-ray galaxy clusters
• The Impact of Galaxy Cluster Mergers on Cosmological Parameter Estimation from Surveys of the Sunyaev-Zel'dovich Effect
• The galaxy group NGC 507: newly detected AGN remnant plasma transported by sloshing
• Dynamical state of galaxy clusters evaluated from X-ray images
• Applying Wirtinger derivatives to the radio interferometry calibration problem
• Revisiting the radio interferometer measurement equation. IV. A generalized tensor formalism
• Tricolour: an optimized SumThreshold flagger for MeerKAT
• MERGHERS Pilot: MeerKAT discovery of diffuse emission in nine massive Sunyaev-Zel'dovich-selected galaxy clusters from ACT
• Precise Mass Determination of SPT-CL J2106-5844, the Most Massive Cluster at z>1
• The diffuse radio emission in the high-redshift cluster PSZ2 G091.83+26.11: total intensity and polarisation analysis with Very Large Array 1-4 GHz observations
• Limits and challenges of the detection of cluster-scale diffuse radio emission at high redshift: The Massive and Distant Clusters of WISE Survey (MaDCoWS) in LoTSS-DR2
• MeerKAT's discovery of a radio relic in the bimodal merging cluster A2384
• The effect of dynamical states on galaxy clusters populations. I. Classification of dynamical states

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