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

Understand

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.