Imaging the Schwarzschild-radius-scale Structure of M87 with the Event Horizon Telescope using Sparse Modeling

Abstract

We propose a new imaging technique for radio and optical/infrared interferometry. The proposed technique reconstructs the image from the visibility amplitude and closure phase, which are standard data products of short-millimeter very long baseline interferometers such as the Event Horizon Telescope (EHT) and optical/infrared interferometers, by utilizing two regularization functions: the ${\ell }_1$-norm and total variation (TV) of the brightness distribution. In the proposed method, optimal regularization parameters, which represent the sparseness and effective spatial resolution of the image, are derived from data themselves using cross validation (CV). As an application of this technique, we present simulated observations of M87 with the EHT based on four physically motivated models. We confirm that ${\ell }_1$+TV regularization can achieve an optimal resolution of $\sim 20-30$% of the diffraction limit $\lambda /D_{\max }$, which is the nominal spatial resolution of a radio interferometer. With the proposed technique, the EHT can robustly and reasonably achieve super-resolution sufficient to clearly resolve the black hole shadow. These results make it promising for the EHT to provide an unprecedented view of the event-horizon-scale structure in the vicinity of the super-massive black hole in M87 and also the Galactic center Sgr A*.

16 pages, 6 figures, accepted for publication in ApJ

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• First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole
• First M87 Event Horizon Telescope Results. VII. Polarization of the Ring
• First Sagittarius A* Event Horizon Telescope Results. III: Imaging of the Galactic Center Supermassive Black Hole
• First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass
• A ring-like accretion structure in M87 connecting its black hole and jet
• Event Horizon Telescope observations of the jet launching and collimation in Centaurus A
• Key Science Goals for the Next-Generation Event Horizon Telescope
• Super-resolution Full Polarimetric Imaging for Radio Interferometry with Sparse Modeling
• Faraday rotation in the jet of M87 inside the Bondi radius: indication of winds from hot accretion flows confining the relativistic jet
• Dynamical Imaging with Interferometry
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• Weak gravitational lensing and shadow of a GUP-modified Schwarzschild black hole in the presence of plasma
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• Resolving the inner parsec of the blazar J1924-2914 with the Event Horizon Telescope
• The Extremely Large Telescope
• Multi-frequency Black Hole Imaging for the Next-Generation Event Horizon Telescope
• Collimation of the relativistic jet in the quasar 3C 273
• General relativistic smoothed particle hydrodynamics
• Selective Dynamical Imaging of Interferometric Data
• Black Hole Spin Signature in the Black Hole Shadow of M87 in the Flaring State
• Magnetospheric Gamma-Ray Emission in Active Galactic Nuclei
• The Event Horizon Telescope Image of the Quasar NRAO 530
• The intrinsic structure of Sagittarius A* at 1.3 cm and 7 mm
• Einstein Quartic Gravity: Shadows, Signals, and Stability
• Rapidly rotating neutron stars in $f(R,T)$ gravity
• Global Mapping of an Exo-Earth using Sparse Modeling
• RadioAstron discovery of a mini-cocoon around the restarted parsec-scale jet in 3C 84
• A Mechanism for Triple-Ridge Emission Structure of AGN Jets
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• ALMA Super-resolution Imaging of T Tau: r = 12 au Gap in the Compact Dust Disk around T Tau N
• The observer-dependent shadow of the Kerr black hole
• Multi-scale and Multi-directional VLBI Imaging with CLEAN
• Accretion Burst Echoes as Probes of Protostellar Environments and Episodic Mass Assembly
• Super-resolution Imaging of the Protoplanetary Disk HD 142527 Using Sparse Modeling
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• Dynamic and polarimetric VLBI imaging with a multiscalar approach
• Time-dependent visibility modelling of a relativistic jet in the X-ray binary MAXI J1803-298
• Regularized Maximum Likelihood Image Synthesis and Validation for ALMA Continuum Observations of Protoplanetary Disks
• Search for Alignment of Disk Orientations in Nearby Star-Forming Regions: Lupus, Taurus, Upper Scorpius, $\rho$ Ophiuchi, and Orion
• CLEAN imaging systematics of M87 radio jet
• Imaging a ring-like structure and the extended jet of M87 at 86 GHz
• exoALMA. VIII. Probabilistic Moment Maps and Data Products using Non-parametric Linear Models
• Lensing Signatures of a Slowly-Accelerated Black Hole
• Event-horizon-scale Imaging of M87* under Different Assumptions via Deep Generative Image Priors
• Swarm intelligence for full Stokes dynamic imaging reconstruction of interferometric data
• PolyCLEAN: Atomic Optimization for Super-Resolution Imaging and Uncertainty Estimation in Radio Interferometry
• A Jet Source of Event Horizon Telescope Correlated Flux in M87
• Prospects of using closure traces directly for imaging in Very Long Baseline Interferometry
• Super-Resolved Image of M87 Observed with East Asian VLBI Network
• Gravito-thermal transports, Onsager reciprocal relation and gravitational Wiedemann-Franz law
• Robust analysis of differential Faraday Rotation based on interferometric closure observables
• Origin of the ring ellipticity in the black hole images of M87*
• Probing Einstein-Maxwell-Scalar Black hole via Thin Accretion Disks and Shadows with EHT Observations of M87* and Sgr A*
• Probing circular polarization and magnetic field structure in AGN
• New Views of Black Holes from Computational Imaging
• Accelerating the CLEAN algorithm of radio interferometry with convex optimization
• gSeaGen code by KM3NeT: an efficient tool to propagate muons simulated with CORSIKA
• Investigating the Disk-Jet Structure in M87 through Flux Separation in the Linear and Circular Polarization Images
• Measuring black hole spin through gravitational lensing of pulsars
• Massive black holes and their galaxies
• Multiobjective optimization for scattering mitigation and scattering screen reconstruction in VLBI observations of the Galactic Center
• DoG-HiT: A novel VLBI Multiscale Imaging Approach
• Typical reconstruction limit and phase transition of maximum entropy method