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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Cited by in corpus (35)

• 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 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
• Hybrid Very Long Baseline Interferometry Imaging and Modeling with Themis
• Absorption of electromagnetic and gravitational waves by Kerr black holes: Shadows, superradiance and the spin-helicity effect
• Resolving the inner parsec of the blazar J1924-2914 with the Event Horizon Telescope
• General relativistic smoothed particle hydrodynamics
• Selective Dynamical Imaging of Interferometric Data
• Magnetospheric Gamma-Ray Emission in Active Galactic Nuclei
• Black Hole Spin Signature in the Black Hole Shadow of M87 in the Flaring State
• 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
• Global Mapping of an Exo-Earth using Sparse Modeling
• A Mechanism for Triple-Ridge Emission Structure of AGN Jets
• 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
• Discovery of Limb Brightening in the Parsec-scale Jet of NGC 315 through Global Very Long Baseline Interferometry Observations and Its Implications for Jet Models
• 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
• Search for Alignment of Disk Orientations in Nearby Star-Forming Regions: Lupus, Taurus, Upper Scorpius, $\rho$ Ophiuchi, and Orion
• Prospects of using closure traces directly for imaging in Very Long Baseline Interferometry
• A Jet Source of Event Horizon Telescope Correlated Flux in M87
• Super-Resolved Image of M87 Observed with East Asian VLBI Network
• Robust analysis of differential Faraday Rotation based on interferometric closure observables
• Investigating the Disk-Jet Structure in M87 through Flux Separation in the Linear and Circular Polarization Images