Mining Mini-Halos with MeerKAT I. Calibration and Imaging

Abstract

Radio mini-halos are clouds of diffuse, low surface brightness synchrotron emission that surround the Brightest Cluster Galaxy (BCG) in massive cool-core galaxy clusters. In this paper, we use third generation calibration (3GC), also called direction-dependent (DD) calibration, and point source subtraction on MeerKAT extragalactic continuum data. We calibrate and image archival MeerKAT L-band observations of a sample of five galaxy clusters (ACO 1413, ACO 1795, ACO 3444, MACS J1115.8+0129, MACS J2140.2-2339). We use the CARACal pipeline for direction-independent (DI) calibration, DDFacet and killMS for 3GC, followed by visibility-plane point source subtraction to image the underlying mini-halo without bias from any embedded sources. Our 3GC process shows a drastic improvement in artefact removal, to the extent that the local noise around severely affected sources was halved and ultimately resulted in a 7\% improvement in global image noise. Thereafter, using these spectrally deconvolved Stokes I continuum images, we directly measure for four mini-halos the flux density, radio power, size and in-band integrated spectra. Further to that, we show the in-band spectral index maps of the mini-halo (with point sources). We present a new mini-halo detection hosted by MACS J2140.2-2339, having flux density $S_{1.28\mathrm{GHz}}=2.61\pm 0.31$ mJy, average diameter 296 kpc and ${\alpha }_{1\mathrm{GHz}}^{1.5\mathrm{GHz}}=1.21\pm 0.36$. We also found a $\sim$100 kpc southern extension to the ACO 3444 mini-halo which was not detected in previous VLA L-band observations. Our description of MeerKAT wide-field, wide-band data reduction will be instructive for conducting further mini-halo science.

arXiv comment16 pages. 10 figures

References in corpus (52)

• WSClean: an implementation of a fast, generic wide-field imager for radio astronomy
• Clusters of galaxies : observational properties of the diffuse radio emission
• The MCXC: a Meta-Catalogue of X-ray detected Clusters of galaxies
• Intracluster Medium Entropy Profiles for a Chandra Archival Sample of Galaxy Clusters
• Planck 2013 results. XXIX. Planck catalogue of Sunyaev-Zeldovich sources
• Diffuse Radio Emission from Galaxy Clusters
• An Accurate Flux Density Scale from 50 MHz to 50 GHz
• An optimized algorithm for multi-scale wideband deconvolution of radio astronomical images
• Revisiting the radio interferometer measurement equation. I. A full-sky Jones formalism
• Faceting for direction-dependent spectral deconvolution
• The X-ray brightest clusters of galaxies from the Massive Cluster Survey
• Radio interferometric gain calibration as a complex optimization problem
• GMRT Radio Halo Survey in galaxy clusters at z = 0.2 -- 0.4 I.The REFLEX sub--sample
• Turbulence and Radio Mini-halos in the Sloshing Cores of Galaxy Clusters
• Evidence for AGN Feedback in Galaxy Clusters and Groups
• Spectral ageing in the lobes of FR-II radio galaxies: New methods of analysis for broadband radio data
• Non-linear Kalman filters for calibration in radio interferometry
• The MeerKAT Galaxy Cluster Legacy Survey I. Survey Overview and Highlights
• CubiCal - Fast radio interferometric calibration suite exploiting complex optimisation
• Revisiting the radio interferometer measurement equation. II. Calibration and direction-dependent effects
• CLASH: A Census of Magnified Star-Forming Galaxies at z ~ 6-8
• The MeqTrees software system and its use for third-generation calibration of radio interferometers
• New scaling relations in cluster radio halos and the re-acceleration model
• New detections of radio minihalos in cool cores of galaxy clusters
• Occurrence of radio minihalos in a mass-limited sample of galaxy clusters
• A search for diffuse radio emission in the relaxed, cool-core galaxy clusters A1068, A1413, A1650, A1835, A2029, and Ophiuchus
• Spectral ageing in the lobes of cluster-centre FR-II radio galaxies
• A LOFAR study of non-merging massive galaxy clusters
• Primary beam effects of radio astronomy antennas -- II. Modelling the MeerKAT L-band beam
• Cosmic ray heating in cool core clusters - II. Self-regulation cycle and non-thermal emission
• Cosmic ray heating in cool core clusters - I. Diversity of steady state solutions
• Expanding the sample of radio minihalos in galaxy clusters
• Calibration artefacts in radio interferometry. I. Ghost sources in WSRT data
• Mapping the particle acceleration in the cool core of the galaxy cluster RX J1720.1+2638
• Revisiting the radio interferometer measurement equation. III. Addressing direction-dependent effects in 21 cm WSRT observations of 3C 147
• The ultra-steep diffuse radio emission observed in the cool-core cluster RX J1720.1+2638 with LOFAR at 54 MHz
• On the relation between mini-halos and AGN feedback in clusters of galaxies
• Testing Secondary Models for the Origin of Radio Mini-Halos in Galaxy Clusters
• Applying Wirtinger derivatives to the radio interferometry calibration problem
• A MeerKAT-meets-LOFAR Study of MS 1455.0+2232: A 590 kiloparsec 'Mini'-Halo in a Sloshing Cool-Core Cluster
• Revisiting the radio interferometer measurement equation. IV. A generalized tensor formalism
• Tricolour: an optimized SumThreshold flagger for MeerKAT
• MeerKAT Primary Beam Measurements in the L Band
• Primary beam effects of radio astronomy antennas: I. Modelling the Karl G. Jansky Very Large Array (VLA) L-band beam using holography
• A LOFAR view into the stormy environment of the galaxy cluster 2A0335+096
• Diffuse Radio Sources in a Statistically Complete Sample of High Redshift Galaxy Clusters
• JVLA 1.5GHz continuum observation of CLASH clusters I: radio properties of the BCGs
• Radio-continuum surveys with SKA and LOFAR: a first look at the perspectives for radio mini-halos
• Signatures of multiple episodes of AGN activity in the core of Abell 1795
• Extended radio emission in the galaxy cluster MS 0735.6+7421 detected with the Karl G. Jansky Very Large Array
• Non-thermal emission and dynamical state of massive galaxy clusters from CLASH sample
• Sub-kpc radio jets in the brightest central galaxy of the cool-core galaxy cluster RXJ1720.1+2638

Cited by in corpus (3)

• A MeerKAT-meets-LOFAR study of Abell 1413: a moderately disturbed non-cool-core cluster hosting a $\sim 500$ kpc 'mini'-halo
• The prototypical major cluster merger Abell 754. I. Calibration of MeerKAT data and radio/X-ray spectral mapping of the cluster
• Probing the evolution of galaxy clusters using SZ effect and non-thermal emission: first results from A1413