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Reconstructing Video from Interferometric Measurements of Time-Varying Sources

Bouman, Katherine L. and Johnson, Michael D. and Dalca, Adrian V. and Chael, Andrew A. and Roelofs, Freek and Doeleman, Sheperd S. and Freeman, William T. (2017) Reconstructing Video from Interferometric Measurements of Time-Varying Sources. . (Unpublished)

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Very long baseline interferometry (VLBI) makes it possible to recover images of astronomical sources with extremely high angular resolution. Most recently, the Event Horizon Telescope (EHT) has extended VLBI to short millimeter wavelengths with a goal of achieving angular resolution sufficient for imaging the event horizons of nearby supermassive black holes. VLBI provides measurements related to the underlying source image through a sparse set spatial frequencies. An image can then be recovered from these measurements by making assumptions about the underlying image. One of the most important assumptions made by conventional imaging methods is that over the course of a night's observation the image is static. However, for quickly evolving sources, such as the galactic center's supermassive black hole (Sgr A*) targeted by the EHT, this assumption is violated and these conventional imaging approaches fail. In this work we propose a new way to model VLBI measurements that allows us to recover both the appearance and dynamics of an evolving source by reconstructing a video rather than a static image. By modeling VLBI measurements using a Gaussian Markov Model, we are able to propagate information across observations in time to reconstruct a video, while simultaneously learning about the dynamics of the source's emission region. We demonstrate our proposed Expectation-Maximization (EM) algorithm, StarWarps, on realistic synthetic observations of black holes, and show how it substantially improves results compared to conventional imaging algorithms. Additionally, we demonstrate StarWarps on real VLBI data of the M87 Jet from the VLBA.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Bouman, Katherine L.0000-0003-0077-4367
Johnson, Michael D.0000-0002-4120-3029
Dalca, Adrian V.0000-0002-8422-0136
Chael, Andrew A.0000-0003-2966-6220
Roelofs, Freek0000-0001-5461-3687
Doeleman, Sheperd S.0000-0002-9031-0904
Freeman, William T.0000-0002-2231-7995
Group:Astronomy Department
Record Number:CaltechAUTHORS:20190405-150420502
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94509
Deposited By: George Porter
Deposited On:05 Apr 2019 22:31
Last Modified:02 Jun 2023 00:35

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