Constraints on the magnetic field in the inter-cluster bridge A399-A401

Abstract

Galaxy cluster mergers are natural consequences of the structure formation in the Universe. Such events involve a large amount of energy ($\sim 10^{63}$ erg) dissipated during the process. Part of this energy can be channelled in particle acceleration and magnetic field amplification, enhancing non-thermal emission of the intra- and inter-cluster environment. Recently, low-frequency observations have detected a bridge of diffuse synchrotron emission connecting two merging galaxy clusters, Abell 399 and Abell 401. Such a result provides clear observational evidence of relativistic particles and magnetic fields in-between clusters. In this work, we have used LOw Frequency ARray (LOFAR) observations at 144 MHz to study for the first time the polarized emission in the A399-A401 bridge region. No polarized emission was detected from the bridge region. Assuming a model where polarization is generated by multiple shocks, depolarization can be due to Faraday dispersion in the foreground medium with respect to the shocks. We constrained its Faraday dispersion to be greater than 0.10 rad m${}^{-2}$ at 95% confidence level, which corresponds to an average magnetic field of the bridge region greater than 0.46 nG (or 0.41 nG if we include regions of the Faraday spectrum that are contaminated by Galactic emission). This result is largely consistent with the predictions from numerical simulations for Mpc regions where the gas density is $\sim 300$ times larger than the mean gas density.

12 pages, 13 figures; accepted in A&A

References in corpus (32)

• WSClean: an implementation of a fast, generic wide-field imager for radio astronomy
• The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release
• The LOFAR Two-metre Sky Survey -- V. Second data release
• Diffuse Radio Emission from Galaxy Clusters
• An optimized algorithm for multi-scale wideband deconvolution of radio astronomical images
• GMRT Radio Halo Survey in galaxy clusters at z = 0.2 -- 0.4. II.The eBCS clusters and analysis of the complete sample
• Shock Waves in Eulerian Cosmological Simulations: Main Properties and Acceleration of Cosmic Rays
• A radio ridge connecting two galaxy clusters in a filament of the cosmic web
• Resolved magnetic dynamo action in the simulated intracluster medium
• Simulations of extragalactic magnetic fields and of their observables
• Second order Fermi reacceleration mechanisms and large scale synchrotron radio emission in intra-cluster bridges
• Gas and galaxies in filament between clusters of galaxies: The study of A399-A401
• Dynamical evolution of magnetic fields in the intracluster medium
• Differences in Faraday Rotation Between Adjacent Extragalactic Radio Sources as a Probe of Cosmic Magnetic Fields
• Dissecting nonthermal emission in the complex multiple-merger galaxy cluster Abell 2744: Radio and X-ray analysis
• Magnetic field strength in cosmic web filaments
• On the absence of radio halos in clusters with double relics
• Galaxy clusters enveloped by vast volumes of relativistic electrons
• The Faraday Rotation Measure Grid of the LOFAR Two-metre Sky Survey: Data Release 2
• Magnetic fields and relativistic electrons fill entire galaxy cluster
• Radio footprints of a minor merger in the Shapley Supercluster: From supercluster down to galactic scales
• Magnetic field evolution in cosmic filaments with LOFAR data
• Physical insights from the spectrum of the radio halo in MACS J0717.5+3745
• Polarisation of Radio Relics in Galaxy Clusters
• Diffuse polarized emission in the LOFAR Two-meter Sky Survey
• Constraints on primordial magnetic fields from magnetically-induced perturbations: current status and future perspectives with LiteBIRD and future ground based experiments
• Polarized accretion shocks from the cosmic web
• Faraday tomography of LoTSS-DR2 data: I. Faraday moments in the high-latitude outer Galaxy and revealing Loop III in polarisation
• The thermal and non-thermal components within and between galaxy clusters Abell 399 and Abell 401
• A search for inter-cluster filaments with LOFAR and eROSITA
• Stacking the Synchrotron Cosmic Web with FIGARO
• Radio multifrequency observations of galaxy clusters. The Abell 399$-$401 pair

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