Bayesian Accretion Modeling: Axisymmetric Equatorial Emission in the Kerr Spacetime

Abstract

The Event Horizon Telescope (EHT) has produced images of two supermassive black holes, Messier~87* (M 87*) and Sagittarius~A* (Sgr A*). The EHT collaboration used these images to indirectly constrain black hole parameters by calibrating measurements of the sky-plane emission morphology to images of general relativistic magnetohydrodynamic (GRMHD) simulations. Here, we develop a model for directly constraining the black hole mass, spin, and inclination through signatures of lensing, redshift, and frame dragging, while simultaneously marginalizing over the unknown accretion and emission properties. By assuming optically thin, axisymmetric, equatorial emission near the black hole, our model gains orders of magnitude in speed over similar approaches that require radiative transfer. Using 2017 EHT M 87* baseline coverage, we use fits of the model to itself to show that the data are insufficient to demonstrate existence of the photon ring. We then survey time-averaged GRMHD simulations fitting EHT-like data, and find that our model is best-suited to fitting magnetically arrested disks, which are the favored class of simulations for both M 87* and Sgr A*. For these simulations, the best-fit model parameters are within $\sim 10\%$ of the true mass and within $\sim 10^{\circ }$ for inclination. With 2017 EHT coverage and 1\% fractional uncertainty on amplitudes, spin is unconstrained. Accurate inference of spin axis position angle depends strongly on spin and electron temperature. Our results show the promise of directly constraining black hole spacetimes with interferometric data, but they also show that nearly identical images permit large differences in black hole properties, highlighting degeneracies between the plasma properties, spacetime, and most crucially, the unknown emission geometry when studying lensed accretion flow images at a single frequency.

arXiv commentAccepted to ApJ, 16 pages, 10 figures

References in corpus (52)

• Array Programming with NumPy
• First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
• Advection-Dominated Accretion: A Self-Similar Solution
• dynesty: A Dynamic Nested Sampling Package for Estimating Bayesian Posteriors and Evidences
• First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
• First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole
• Advection-Dominated Accretion: Underfed Black Holes and Neutron Stars
• First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole
• Hot Accretion Flows Around Black Holes
• 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
• A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty
• HARM: A Numerical Scheme for General Relativistic Magnetohydrodynamics
• Magnetically Arrested Disk: An Energetically Efficient Accretion Flow
• First M87 Event Horizon Telescope Results. VIII. Magnetic Field Structure near The Event Horizon
• First Sagittarius A* Event Horizon Telescope Results. VI: Testing the Black Hole Metric
• Black Hole Shadows, Photon Rings, and Lensing Rings
• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
• Three-dimensional MHD Simulations of Radiatively Inefficient Accretion Flows
• GRMHD Simulations of Magnetized Advection Dominated Accretion on a Non-Spinning Black Hole: Role of Outflows
• First M87 Event Horizon Telescope Results. VII. Polarization of the Ring
• The Black-Hole Mass in M87 from Gemini/NIFS Adaptive Optics Observations
• First Sagittarius A* Event Horizon Telescope Results. III: Imaging of the Galactic Center Supermassive Black Hole
• Testing the No-Hair Theorem with Observations in the Electromagnetic Spectrum: II. Black-Hole Images
• First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multi-wavelength Observations, Data Processing, and Calibration
• Universal Interferometric Signatures of a Black Hole's Photon Ring
• First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass
• The Structure and Dynamics of the Sub-parsec Scale Jet in M87 Based on 50 VLBA Observations Over 17 Years at 43 GHz
• General relativistic magnetohydrodynamical simulations of the jet in M87
• The M87 Black Hole Mass from Gas-dynamical Models of Space Telescope Imaging Spectrograph Observations
• Shapes and Positions of Black Hole Shadows in Accretion Disks and Spin Parameters of Black Holes
• Interferometric Imaging Directly with Closure Phases and Closure Amplitudes
• Lensing by Kerr Black Holes
• Testing the No-Hair Theorem with Event Horizon Telescope Observations of Sagittarius A*
• A Fast New Public Code for Computing Photon Orbits in a Kerr Spacetime
• The `quiescent' black hole in M87
• Observing the Inner Shadow of a Black Hole: A Direct View of the Event Horizon
• Evidence for Low Black Hole Spin and Physically Motivated Accretion Models from Millimeter VLBI Observations of Sagittarius A*
• Estimating the Parameters of Sgr A*'s Accretion Flow Via Millimeter VLBI
• The Null Geodesics of the Kerr Exterior
• Universal Polarimetric Signatures of the Black Hole Photon Ring
• Modeling Seven Years of Event Horizon Telescope Observations with Radiatively Inefficient Accretion Flow Models
• The Polarized Image of a Synchrotron Emitting Ring of Gas Orbiting a Black Hole
• Polarized Image of Equatorial Emission in the Kerr Geometry
• Precise radio astrometry and new developments for the next generation of instruments
• The Effects of Accretion Flow Dynamics on the Black Hole Shadow of Sagittarius A${}^{\ast }$
• Iharm3D: Vectorized General Relativistic Magnetohydrodynamics
• Probing the innermost accretion flow geometry of Sgr A* with Event Horizon Telescope
• Decomposing the Internal Faraday Rotation of Black Hole Accretion Flows
• The Jet-Disk Boundary Layer in Black Hole Accretion
• Spacetime Tomography Using The Event Horizon Telescope

Cited by in corpus (10)

• Key Science Goals for the Next-Generation Event Horizon Telescope
• The Black Hole Explorer: Motivation and Vision
• The Black Hole Explorer: Photon Ring Science, Detection and Shape Measurement
• Fitting the light curves of Sagittarius A* with a hot-spot model
• Bayesian Black Hole Photogrammetry
• Deep learning inference with the Event Horizon Telescope II. The Zingularity framework for Bayesian artificial neural networks
• $\text{Jipole}$: A Differentiable $\text{ipole}$-based Code for Radiative Transfer in Curved Spacetimes
• Assessing the Role of Intrinsic Variability in Black Hole Parameter Inference using Multi-Epoch EHT Data
• $\text{GPUmonty}$: A GPU-accelerated relativistic Monte Carlo radiative transfer code
• Extreme-Lensing Signatures Revealed by Correlations of Simulated Black-Hole Movies