A three-component giant radio halo: the puzzling case of the galaxy cluster Abell 2142

Abstract

Turbulence introduced into the intra-cluster medium (ICM) through cluster merger events transfers energy to non-thermal components, and can trigger the formation of diffuse synchrotron radio sources. Typical diffuse sources in the forms of giant radio halos and mini-halos are found in merging and relaxed cool core galaxy clusters, respectively. On the other hand, recent observations have revealed an increasing complexity of the non-thermal phenomenology. Abell 2142 (A2142) is a mildly disturbed cluster that exhibits uncommon thermal and non-thermal properties. It is known to host a hybrid halo consisting of two components (H1 and H2), namely a mini-halo-like and an enigmatic elongated radio halo-like structure. We aim to investigate the properties, origin, and connections of each component. We present deep LOFAR observations of A2142 in the frequency ranges $30-78$ MHz and $120-168$ MHz. With complementary multi-frequency radio and X-ray data, we analyse the radio spectral properties of the halo and assess the connection between the non-thermal and thermal components of the ICM. We detected a third radio component (H3), which extends over the cluster volume on scales $\sim 2$ Mpc, embeds H1 and H2, and has a morphology that roughly follows the thermal ICM distribution. The radio spectral index is moderately steep in H1 ($\alpha =1.09\pm 0.02$) and H2 ($\alpha =1.15\pm 0.02$), but is steeper ($\alpha =1.57\pm 0.20$) in H3. The analysis of the thermal and non-thermal properties allowed us to discuss possible formation scenarios for each radio component. Turbulence from sloshing motions of low-entropy gas on different scales may be responsible for the origin of H1 and H2. We classified H3 as a giant ultra-steep spectrum radio halo, which could trace the residual activity from an old energetic merger and/or inefficient turbulent re-acceleration induced by ongoing minor mergers.

24 pages (including Appendix), 15 Figures (plus 4 Figures in Appendix), Accepted for publication by A&A

References in corpus (54)

• Array Programming with NumPy
• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• WSClean: an implementation of a fast, generic wide-field imager for radio astronomy
• Shocks and cold fronts in galaxy clusters
• The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release
• Intracluster Medium Entropy Profiles for a Chandra Archival Sample of Galaxy Clusters
• The LOFAR Two-metre Sky Survey -- V. Second data release
• Diffuse Radio Emission from Galaxy Clusters
• Compressible Turbulence in Galaxy Clusters: Physics and Stochastic Particle Re-acceleration
• On the connection between giant radio halos and cluster mergers
• An optimized algorithm for multi-scale wideband deconvolution of radio astronomical images
• A low-frequency radio halo associated with a cluster of galaxies
• The LOFAR Two Meter Sky Survey: Deep Fields, I -- Direction-dependent calibration and imaging
• Contour binning: a new technique for spatially-resolved X-ray spectroscopy applied to Cassiopeia A
• Radio interferometric gain calibration as a complex optimization problem
• The Case for Electron Re-Acceleration at Galaxy Cluster Shocks
• Statistics of Giant Radio Halos from Electron Reacceleration Models
• Simulating cosmic rays in clusters of galaxies - II. A unified scheme for radio halos and relics with predictions of the gamma-ray emission
• A radio ridge connecting two galaxy clusters in a filament of the cosmic web
• Do radio core-halos and cold fronts in non major merging clusters originate from the same gas sloshing?
• LOFAR observations of galaxy clusters in HETDEX
• Non-linear Kalman filters for calibration in radio interferometry
• Turbulence and Particle Acceleration in Giant Radio Haloes: the Origin of Seed Electrons
• Relativistic protons in the Coma galaxy cluster: first gamma-ray constraints ever on turbulent reacceleration
• The LOFAR LBA Sky Survey I. survey description and preliminary data release
• The Matryoshka Run (II): Time Dependent Turbulence Statistics, Stochastic Particle Acceleration and Microphysics Impact in a Massive Galaxy Cluster
• A giant radio halo in the cool core cluster CL1821+643
• CAPTURE: A continuum imaging pipeline for the uGMRT
• Radio halos in a mass-selected sample of 75 galaxy clusters. II. Statistical analysis
• Dissecting nonthermal emission in the complex multiple-merger galaxy cluster Abell 2744: Radio and X-ray analysis
• A cluster in a crowded environment: XMM-Newton and Chandra observations of A3558
• Nonthermal Emission Associated with Strong AGN Outbursts at the Centers of Galaxy Clusters
• Galaxy clusters enveloped by vast volumes of relativistic electrons
• Magnetic fields and relativistic electrons fill entire galaxy cluster
• The ultra-steep diffuse radio emission observed in the cool-core cluster RX J1720.1+2638 with LOFAR at 54 MHz
• Physical insights from the spectrum of the radio halo in MACS J0717.5+3745
• Cassiopeia A, Cygnus A, Taurus A, and Virgo A at ultra-low radio frequencies
• Radio and X-ray connection in radio mini-halos: implications for hadronic models
• The Planck clusters in the LOFAR sky: IV: LoTSS-DR2: statistics of radio halos and re-acceleration models
• The LOFAR LBA Sky Survey II. First data release
• Multiscale cosmic web detachments, connectivity, and preprocessing in the supercluster SClA2142 cocoon
• The contribution of discrete sources to the sky temperature at 144 MHz
• The LOFAR and JVLA view of the distant steep spectrum radio halo in MACS J1149.5+2223
• Testing Secondary Models for the Origin of Radio Mini-Halos in Galaxy Clusters
• MWA and ASKAP observations of atypical radio-halo-hosting galaxy clusters: Abell 141 and Abell 3404
• A MeerKAT-meets-LOFAR Study of MS 1455.0+2232: A 590 kiloparsec 'Mini'-Halo in a Sloshing Cool-Core Cluster
• A radio halo surrounding the Brightest Cluster Galaxy in RXCJ0232.2-4420: a mini-halo in transition ?
• Abell 1033: Radio halo and gently reenergized tail at 54 MHz
• Deep low-frequency radio observations of Abell 2256 II: The ultra-steep spectrum radio halo
• Particle re-acceleration and diffuse radio sources in the galaxy cluster Abell 1550
• Surface brightness discontinuities in radio halos. Insights from the MeerKAT Galaxy Cluster Legacy Survey
• Diffuse radio emission in the galaxy cluster SPT-CL J2031-4037: a steep spectrum intermediate radio halo?
• Introducing PT-REX, the Point-to-point TRend EXtractor
• The evolving cluster cores: Putting together the pieces of the puzzle

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• Radio emission from a massive node of the cosmic web. A discovery powered by machine learning
• uGMRT and MeerKAT observation of RXCJ0232-4420: a quiet cluster with a giant radio halo
• Discovery of large-scale radio emission enveloping the mini-halo in the most X-ray luminous galaxy cluster RX~J1347.5-1145
• A group of merging galaxies falling onto Abell 2142