Cosmological simulation of a radio synchrotron bridge between pre-merging galaxy clusters

Abstract

Radio bridges are diffuse synchrotron emission observed between merging galaxy clusters. Recent radio observations have reported both detections and non-detections of radio bridges between clusters. The detections imply the presence of cosmic rays (CRs) and magnetic fields permeating the cosmic web that produce synchrotron emission observable with current facilities, whereas the non-detections suggest that specific physical conditions are required for their formation. We study the CR reacceleration by solenoidal turbulence in the filament connecting two massive clusters at an early stage of the merger. Our aim is to test whether this mechanism can generate diffuse emission in the inter-cluster region. We perform a cosmological magneto-hydrodynamical (MHD) simulation using the Enzo code. We improved a run-time Lagrangian tracer method implemented in Enzo, and follow the trajectories of baryonic matter using $N=\mathcal{O}(10^7)$ tracer particles. In post-processing, we conduct a parallel computation of the Fokker-Planck (FP) equation for all tracers, with cooling and reacceleration efficiencies evaluated from the local quantities recorded along each tracer trajectory. Our simulation generate a Mpc-sized radio bridge in the early stage of the cluster merger. Within a reasonable parameter range, the reacceleration model produces a broad variety of spectra. In our fiducial model, the simulated bridge matches several properties of the one found between Abell 399 and Abell 401, such as its spectral shape, intensity profile, and pixel-by-pixel correlation between radio and X-ray intensities. The inter-cluster region is filled with turbulence induced by infalling mass clumps and subsequently amplified by the approaching motion of the clusters. The CR reacceleration by the turbulence is a viable mechanism to power a Mpc-sized synchrotron emission observed as radio bridges.

21 pages, 15 figures, accepted for publication in A&A

References in corpus (45)

• Diffuse Radio Emission from Galaxy Clusters
• Turbulence and Magnetic Fields in the Large Scale Structure of the Universe
• Compressible Turbulence in Galaxy Clusters: Physics and Stochastic Particle Re-acceleration
• Detecting shock waves in cosmological smoothed particle hydrodynamics simulations
• Hydrodynamic Simulation of Non-thermal Pressure Profiles of Galaxy Clusters
• Detection of hot gas in the filament connecting the clusters of galaxies Abell 222 and Abell 223
• A radio ridge connecting two galaxy clusters in a filament of the cosmic web
• Resolved magnetic dynamo action in the simulated intracluster medium
• Cosmological Shock Waves in the Large Scale Structure of the Universe: Non-gravitational Effects
• Turbulence and Vorticity in Galaxy Clusters Generated by Structure Formation
• 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
• Deep VLA observations of the cluster 1RXS J0603.3+4214 in the frequency range 1-2 GHz
• 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
• The Abell 3391/95 galaxy cluster system: A 15 Mpc intergalactic medium emission filament, a warm gas bridge, infalling matter clumps, and (re-) accelerated plasma discovered by combining SRG/eROSITA data with ASKAP/EMU and DECam data
• First detection of stacked X-ray emission from cosmic web filaments
• Testing cosmic-ray acceleration with radio relics: a high-resolution study using MHD and tracers
• First Predicted Cosmic Ray Spectra, Primary-to-Secondary Ratios, and Ionization Rates from MHD Galaxy Formation Simulations
• The Coma cluster at LOFAR frequencies I: insights into particle acceleration mechanisms in the radio bridge
• Galaxy clusters enveloped by vast volumes of relativistic electrons
• Magnetic fields and relativistic electrons fill entire galaxy cluster
• Shocks and non-thermal particles in clusters of galaxies
• 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
• Radio and X-ray connection in radio mini-halos: implications for hadronic models
• Radio observations of the merging galaxy cluster system Abell 3391-Abell 3395
• An Efficient Fokker-Planck Solver and its Application to Stochastic Particle Acceleration in Galaxy Clusters
• CRESCENDO: An on-the-fly Fokker-Planck Solver for Spectral Cosmic Rays in Cosmological Simulations
• LOFAR high-band antenna observations of the Perseus cluster
• Life cycle of cosmic-ray electrons in the intracluster medium
• Discovery of a pre-merger shock in an intercluster filament in Abell 98
• The eROSITA view of the Abell 3391/95 field: Cluster Outskirts and Filaments
• A detailed study of the bridge of excess X-ray emission between the galaxy clusters Abell 2029 and Abell 2033
• The thermal and non-thermal components within and between galaxy clusters Abell 399 and Abell 401
• The evolution of cosmic ray electrons in the cosmic web: seeding by AGN, star formation and shocks
• Discovery of a >13 Mpc long X-ray filament between two galaxy clusters beyond three times their virial radii
• A multishock scenario for the formation of radio relics
• Vortex-p: a Helmholtz-Hodge and Reynolds decomposition algorithm for particle-based simulations
• Cosmological simulations of the generation of cluster-scale radio emission from turbulent re-acceleration
• Jet interaction with galaxy cluster mergers
• Abell 0399-Abell 0401 radio bridge spectral index: the first multifrequency detection
• Radio Observations as a Probe of Cosmic Web Magnetism
• Detection of pure warm-hot intergalactic medium emission from a $7.2$ Mpc long filament in the Shapley supercluster using X-ray spectroscopy
• Cosmological Zoom-In Simulation of Odd Radio Circles as Merger-Driven Shocks in Galaxy Groups