The Polarized Image of a Synchrotron Emitting Ring of Gas Orbiting a Black Hole

Abstract

Synchrotron radiation from hot gas near a black hole results in a polarized image. The image polarization is determined by effects including the orientation of the magnetic field in the emitting region, relativistic motion of the gas, strong gravitational lensing by the black hole, and parallel transport in the curved spacetime. We explore these effects using a simple model of an axisymmetric, equatorial accretion disk around a Schwarzschild black hole. By using an approximate expression for the null geodesics derived by Beloborodov (2002) and conservation of the Walker-Penrose constant, we provide analytic estimates for the image polarization. We test this model using currently favored general relativistic magnetohydrodynamic simulations of M87*, using ring parameters given by the simulations. For a subset of these with modest Faraday effects, we show that the ring model broadly reproduces the polarimetric image morphology. Our model also predicts the polarization evolution for compact flaring regions, such as those observed from Sgr A* with GRAVITY. With suitably chosen parameters, our simple model can reproduce the EVPA pattern and relative polarized intensity in Event Horizon Telescope images of M87*. Under the physically motivated assumption that the magnetic field trails the fluid velocity, this comparison is consistent with the clockwise rotation inferred from total intensity images.

29 pages, 11 figures, published in ApJ on May 3

References in corpus (17)

• First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
• First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole
• First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole
• First M87 Event Horizon Telescope Results. V. Physical Origin of the Asymmetric Ring
• First M87 Event Horizon Telescope Results. II. Array and Instrumentation
• First M87 Event Horizon Telescope Results. III. Data Processing and Calibration
• First M87 Event Horizon Telescope Results. VIII. Magnetic Field Structure near The Event Horizon
• First M87 Event Horizon Telescope Results. VII. Polarization of the Ring
• Lensing by Kerr Black Holes
• Polarimetry of near-infrared flares from Sagittarius A*
• A polarised infrared flare from Sagittarius A* and the signatures of orbiting plasma hotspots
• Discriminating Accretion States via Rotational Symmetry in Simulated Polarimetric Images of M87
• The Submillimeter Polarization of Sgr A*
• Dynamically important magnetic fields near the event horizon of Sgr A*
• Decomposing the Internal Faraday Rotation of Black Hole Accretion Flows
• Predicting the X-ray polarization of type-2 Seyfert galaxies
• Maximum Observable Blueshift from Circular Equatorial Kerr Orbiters

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• Adaptive Analytical Ray Tracing of Black Hole Photon Rings
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• Black Hole Polarimetry I: A Signature of Electromagnetic Energy Extraction
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• Unraveling Twisty Linear Polarization Morphologies in Black Hole Images
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• Bayesian Accretion Modeling: Axisymmetric Equatorial Emission in the Kerr Spacetime
• Image of the Schwarzschild black hole pierced by a cosmic string with a thin accretion disk
• Polarized Images of Synchrotron Radiations in Curved Spacetime
• Signatures of Black Hole Spin and Plasma Acceleration in Jet Polarimetry
• How Spatially Resolved Polarimetry Informs Black Hole Accretion Flow Models
• Study of general relativistic magnetohydrodynamic accretion flow around black holes
• Particle dynamics and the accretion disk around a Self-dual Black Hole immersed in a magnetic field in Loop Quantum Gravity
• Relativistic Signatures of Flux Eruption Events Near Black Holes
• Analytical expressions for pulse profile of neutron stars in plasma environments
• Polarization Observations of AGN Jets: Past and Future
• Bayesian Black Hole Photogrammetry
• Polarimetric Geometric Modeling for mm-VLBI Observations of Black Holes
• Multi-Frequency Models of Black Hole Photon Rings from Low-Luminosity Accretion Disks
• Energy Extraction from Loop Quantum Black Holes: The Role of Magnetic Penrose Process and Quantum Gravity Effects with Astrophysical Insights
• Astrophysical insights into magnetic Penrose process around parameterized Konoplya-Rezzolla-Zhidenko black hole
• Observational Signatures of Black Hole Accretion: Rotating vs. Spherical Flows with Tilted Magnetic Fields
• Electromagnetic signatures of strong-field gravity from accreting black holes
• Accurate analytical modeling of light rays in spherically symmetric spacetimes: Applications in the study of black hole accretion disks and polarimetry
• Semi-analytic studies of accretion disk and magnetic field geometry in M87*
• Did the Event Horizon Telescope Detect the Base of the Sub-Milliarsecond Tubular Jet in M\,87?
• Optical images of the Kerr-Sen black hole and thin accretion disk
• Probing Observable Features of Lorentz violation in Low-Energy Hořava Gravity with Accretion Disk Images of Black Hole
• Effect of nonlinear electrodynamics on polarization distribution around black hole
• Thin accretion disk around Schwarzschild-like black hole in bumblebee gravity
• Characterization of black hole accretion through image moment invariants
• Assessing the Role of Intrinsic Variability in Black Hole Parameter Inference using Multi-Epoch EHT Data
• Photon Ring Symmetries in Simulated Linear Polarization Images of Messier 87*
• Polarization Signatures of Inspiraling Hotspots around Kerr Black Holes
• Fast and accurate analytical formulas for light propagation in general static, spherically symmetric spacetimes
• Polarization Signatures of Rotating Black Holes in Perfect Fluid Dark Matter Spacetimes