Broadband radio polarimetry of Fornax A, I: Depolarized patches generated by advected thermal material from NGC 1316

Abstract

We present observations and analysis of the polarized radio emission from the nearby radio galaxy Fornax A over 1.28--3.1 GHz, using data from the Australia Telescope Compact Array (ATCA). In this, the first of two associated papers, we use modern broadband polarimetric techniques to examine the nature and origin of conspicuous low-polarization (low-$p$) patches in the lobes. We resolve the low-$p$ patches, and find that their low fractional polarization is associated with complicated frequency-dependent interference in the polarized signal generated by Faraday effects along the line of sight. The low-$p$ patches are spatially correlated with interfaces in the magnetic structure of the lobe, across which the line-of-sight-projected magnetic field changes direction. Spatial correlations with the sky-projected magnetic field orientation and structure in total intensity are also identified and discussed. We argue that the low-$p$ patches, along with associated reversals in the line-of-sight magnetic field and other related phenomena, are best explained by the presence of $\mathcal{O}(10^9)$ $M_{\odot }$ of magnetized thermal plasma in the lobes, structured in shells or filaments, and likely advected from the ISM of NCG 1316 or its surrounding ICM. Our study underscores the power and utility of spatially-resolved, broadband, full-polarization radio observations to reveal new facets of flow behaviors and magneto-ionic structure in radio lobes and their interplay with the surrounding environment.

arXiv comment32 pages, 21 figures. Accepted for publication in The Astrophysical Journal on 10 Feb. 2018

References in corpus (72)

• emcee: The MCMC Hammer
• Heating Hot Atmospheres with Active Galactic Nuclei
• Evolution of Buoyant Bubbles in M87
• Faraday Rotation Measure Synthesis
• Mechanical Feedback from Active Galactic Nuclei in Galaxies, Groups, and Clusters
• The Australia Telescope Compact Array Broadband Backend (CABB)
• Post-correlation radio frequency interference classification methods
• Substructure and dynamics of the Fornax Cluster
• Hot Bubbles from Active Galactic Nuclei as a Heat Source in Cooling Flow Clusters
• Draping of Cluster Magnetic Fields over Bullets and Bubbles -- Morphology and Dynamic Effects
• The Westerbork SINGS Survey II. Polarization, Faraday Rotation, and Magnetic Fields
• Dynamical models for jet deceleration in the radio galaxy 3C 31
• The hydrodynamics of dead radio galaxies
• How AGN Jets Heat the Intracluster Medium -- Insights from Hydrodynamic Simulations
• The Magnetic Rayleigh-Taylor Instability in Three Dimensions
• Chemical enrichment in the cluster of galaxies Hydra A
• Chandra X-ray Observations of NGC 1316 (Fornax A)
• Impact of tangled magnetic fields on AGN-blown bubbles
• The MHD Kelvin-Helmholtz Instability: A Two-Dimensional Numerical Study
• Deep ROSAT-HRI observations of the NGC 1399/NGC 1404 region: morphology and structure of the X-ray halo
• Numerical modelling of the lobes of radio galaxies in cluster environments II: Magnetic field configuration and observability
• A very extended molecular web around NGC 1275
• Buoyant radio plasma in clusters of galaxies
• The Energetics and Lifetimes of Local Radio Active Galactic Nuclei
• Structures of the magnetoionic media around the FR I radio galaxies 3C 31 and Hydra A
• Simulating the interaction of jets with the intra-cluster medium
• Infall of the Elliptical Galaxy NGC 1404 into the Fornax Cluster
• ALMA observations of massive molecular gas filaments encasing radio bubbles in the Phoenix cluster
• The Distance to NGC 1316 (Fornax A) From Observations of Four Type Ia Supernovae
• The Fornax Deep Survey with VST. II. Fornax A: a two-phase assembly caught on act
• Nonlinear Evolution of the Magnetohydrodynamic Rayleigh-Taylor Instability
• Fermi Large Area Telescope Detection of Extended Gamma-Ray Emission from the Radio Galaxy Fornax A
• Numerical modelling of the lobes of radio galaxies in cluster environments - III. Powerful relativistic and nonrelativistic jets
• Local simulations of the magnetized Kelvin-Helmholtz instability in neutron-star mergers
• Comparison of algorithms for determination of rotation measure and Faraday structure I. 1100 - 1400 MHz
• Broadband Radio Polarimetry and Faraday Rotation of 563 Extragalactic Radio Sources
• Buoyant Bubbles in Intracluster Gas: Effects of Magnetic Fields and Anisotropic Viscosity
• Thermal plasma in the giant lobes of the radio galaxy Centaurus A
• The Chandra Fornax Survey - I: The Cluster Environment
• Broadband, radio spectro-polarimetric study of 100 radiative-mode and jet-mode AGN
• Atomic and molecular gas in the merger galaxy NGC 1316 (Fornax A) and its environment
• Ordered magnetic fields around radio galaxies: evidence for interaction with the environment
• Viscous Kelvin-Helmholtz instabilities in highly ionised plasmas
• Modelling of the Spectral Energy Distribution of Fornax A: Leptonic and Hadronic Production of High Energy Emission from the Radio Lobes
• A study of broadband Faraday rotation and polarization behaviour over 1.3--10 GHz in 36 discrete radio sources
• Relic Radio Bubbles and Cluster Cooling Flows
• On the interaction of FR-II radio sources with the intracluster medium
• The magnetized medium around the radio galaxy B2 0755+37: an interaction with the intra-group gas
• Constraining the Outburst Properties of the SMBH in Fornax A through X-ray, Infrared, and Radio Observations
• The stability of buoyant bubbles in the atmospheres of galaxy clusters
• On the Rayleigh-Taylor Instability of Radio Bubbles in Galaxy Clusters
• Analytic Detection Thresholds for Measurements of Linearly Polarized Intensity Using Rotation Measure Synthesis
• A Chandra X-ray Analysis of Abell 1664: Cooling, Feedback and Star Formation in the Central Cluster Galaxy
• Mass transport by buoyant bubbles in galaxy clusters
• The Declined Activity in the Nucleus of NGC 1316
• Calibrating Type Ia Supernovae using the Planetary Nebula Luminosity Function I. Initial Results
• Rosat X-ray Observations of the Radio Galaxy NGC 1316 (Fornax A)
• Short Spacing Synthesis from a Primary Beam Scanned Interferometer
• Giant Lobes of Centaurus A Radio Galaxy Observed with the Suzaku X-ray Satellite
• Gentle heating by mixing in cooling flow clusters
• The distance to NGC1316 (Fornax A): yet another curious case
• Hard X-Ray Spectrum from West Lobe of Radio Galaxy Fornax A Observed with Suzaku
• Simulations of multi-phase turbulence in jet cocoons
• Rising Jet-Inflated Bubbles in Clusters of Galaxies
• Violent interaction between the AGN and the hot gas in the core of the galaxy cluster Sersic 159-03
• Three-dimensional magnetohydrodynamic simulations of the evolution of magnetic fields in Fanaroff-Riley class II radio sources
• Which radio galaxies can make the highest-energy cosmic rays?
• Polarization signatures of unresolved radio sources
• The galactic magnetic field in the quasar 3C216
• Evolution of the gas mass fraction in galaxy clusters
• Suzaku Detection of Thermal X-Ray Emission Associated with the Western Radio Lobe of Fornax A
• Looking inside the nest: the hidden structure of the merger galaxy NGC 1316 (Fornax A)

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• Radio galaxies and feedback from AGN jets
• New constraints on the magnetization of the cosmic web using LOFAR Faraday rotation observations
• The intergalactic magnetic field probed by a giant radio galaxy
• The flickering nuclear activity of Fornax A
• Early Science from POSSUM: Shocks, turbulence, and a massive new reservoir of ionised gas in the Fornax cluster
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• The POlarised GLEAM Survey (POGS) I: First Results from a Low-Frequency Radio Linear Polarisation Survey of the Southern Sky
• Neutral hydrogen gas within and around NGC 1316
• Turbulent magnetic fields in the merging galaxy cluster MACS J0717.5+3745: polarization analysis
• Morphology of radio relics II: Properties of polarised emission
• The Quasar Feedback Survey: Revealing the Interplay of Jets, Winds & Emission Line Gas in Type 2 Quasars with Radio Polarization
• Untangling cosmic magnetic fields: Faraday tomography at metre wavelengths with LOFAR
• The Spiderweb proto-cluster is being magnetized by its central radio jet
• Metal-rich trailing outflows uplifted by AGN bubbles in galaxy clusters
• Blazar jet evolution revealed by multi-epoch broadband radio polarimetry
• Faraday rotation study of NGC 612 (PKS 0131-36): a hybrid radio source and its magnetised circumgalactic environment
• A Numerical Study of the Impact of Jet Magnetic Topology on Radio Galaxy Evolution
• Message in a Bottle: Unveiling the Magneto-Ionic Complexity of AGNs through the Stokes QU-Fitting Technique
• A depolarizing HI tidal tail in the western lobe of Fornax A
• A Spectropolarimetric Study of Pictor A Radio Galaxy with MeerKAT
• Observations and Simulations of Radio Emission and Magnetic Fields in Minkowski's Object
• Complex Structure of the Eastern Lobe of the Pictor A Radio Galaxy: Spectral Analysis and X-ray/Radio Correlations