Mpc-scale diffuse radio emission in two massive cool-core clusters of galaxies

Abstract

Radio halos are diffuse synchrotron sources on scales of ~1 Mpc that are found in merging clusters of galaxies, and are believed to be powered by electrons re-accelerated by the merger-driven turbulence. We present measurements of extended radio emission on similarly large scales in two clusters of galaxies hosting cool cores: Abell 2390 and Abell 2261. The analysis is based on interferometric imaging with the JVLA, VLA and GMRT. We present detailed radio images of the targets, subtract the compact emission components, and measure the spectral indices for the diffuse components. The radio emission in A2390 extends beyond a known sloshing-like brightness discontinuity, and has a very steep in-band spectral slope at 1.5 GHz that is similar to some known ultra-steep spectrum radio halos. The diffuse signal in A2261 is more extended than in A2390 but has lower luminosity. X-ray morphological indicators, derived from XMM-Newton X-ray data, place these clusters in the category of relaxed or regular systems, although some asymmetric features that can indicate past minor mergers are seen in the X-ray brightness images. If these two Mpc-scale radio sources are categorized as giant radio halos, they question the common assumption of radio halos occurring exclusively in clusters undergoing violent merging activity, in addition to commonly used criteria in distinguishing between radio halos and mini-halos.

MNRAS submitted, first referee comments incorporated

References in corpus (20)

• Intracluster Medium Entropy Profiles for a Chandra Archival Sample of Galaxy Clusters
• Chandra temperature profiles for a sample of nearby relaxed galaxy clusters
• The Canadian Cluster Comparison Project: detailed study of systematics and updated weak lensing masses
• On the connection between giant radio halos and cluster mergers
• The impact of mergers on relaxed X-ray clusters - I. Dynamical evolution and emergent transient structures
• Images, structural properties and metal abundances of galaxy clusters observed with Chandra ACIS-I at 0.1<z<1.3
• The Very Large Array Low-frequency Sky Survey Redux (VLSSr)
• A low-frequency radio halo associated with a cluster of galaxies
• GMRT Radio Halo Survey in galaxy clusters at z = 0.2 -- 0.4. II.The eBCS clusters and analysis of the complete sample
• Do radio core-halos and cold fronts in non major merging clusters originate from the same gas sloshing?
• Cosmic rays and Radio Halos in galaxy clusters : new constraints from radio observations
• Resurrecting the Red from the Dead: Optical Properties of BCGs in X-ray Luminous Clusters
• The XMM Large Scale Structure survey: The X-ray pipeline and survey selection function
• New scaling relations in cluster radio halos and the re-acceleration model
• The Extended GMRT Radio Halo Survey II: Further results and analysis of the full sample
• A giant radio halo in the cool core cluster CL1821+643
• The impact of mergers on relaxed X-ray clusters - III. Effects on compact cool cores
• Investigating Heating and Cooling in the BCS & B55 Cluster Samples
• Studying the properties of galaxy cluster morphology estimators
• The optical morphology of A3667 re-examined

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• The Planck clusters in the LOFAR sky. I. LoTSS-DR2: new detections and sample overview
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• On the absence of radio halos in clusters with double relics
• New giant radio sources and underluminous radio halos in two galaxy clusters
• On the relation between mini-halos and AGN feedback in clusters of galaxies
• LOFAR high-band antenna observations of the Perseus cluster
• Diffuse Radio Emission from Galaxy Clusters in the LOFAR Two-metre Sky Survey Deep Fields
• A Massive Cluster at z = 0.288 Caught in the Process of Formation: The Case of Abell 959
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• The evolving cluster cores: Putting together the pieces of the puzzle
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• Weak Lensing analysis of Abell 2390 using short exposures
• A spectroscopic survey of Abell 1703: is it a rare relaxed cluster hosting a radio halo or a usual merging system?
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