Closure Traces: Novel Calibration-Insensitive Quantities for Radio Astronomy

Abstract

Closure phases and closure amplitudes have proven critical to modern radio interferometry due to their insensitivity to the uncertain station gains. We present the first set of closure quantities constructed from parallel-hand and cross-hand visibilities that are insensitive to both station gains and to polarimetric leakage. These complex "closure traces" are a natural extension of closure amplitudes and closure phases, are independent of all station-based linear corruptions of the polarized visibilities, and are complete in the sense that they contain all remaining information present in the visibility data. Products of closure traces on so-called "conjugate" quadrangles are sensitive only to structure in the source polarization fraction -- independent of variations in the Stokes $I$ structure -- and thereby provide unambiguous probes of polarization in astronomical sources.

Accepted by ApJ, 15 pages, 6 figures

References in corpus (5)

• First M87 Event Horizon Telescope Results. II. Array and Instrumentation
• First M87 Event Horizon Telescope Results. III. Data Processing and Calibration
• MOJAVE: Monitoring of Jets in AGN with VLBA Experiments. V. Multi-epoch VLBA Images
• MOJAVE: XV. VLBA 15 GHz Total Intensity and Polarization Maps of 437 Parsec-Scale AGN Jets From 1996-2017
• Revisiting the radio interferometer measurement equation. I. A full-sky Jones formalism

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• First M87 Event Horizon Telescope Results. IX. Detection of Near-horizon Circular Polarization
• Invariants in Co-polar Interferometry: an Abelian Gauge Theory
• Invariants in Polarimetric Interferometry: a non-Abelian Gauge Theory
• Polarization Observations of AGN Jets: Past and Future
• Polarimetric Geometric Modeling for mm-VLBI Observations of Black Holes
• A Geometric View of Closure Phases in Interferometry
• Event-horizon-scale Imaging of M87* under Different Assumptions via Deep Generative Image Priors
• Deep learning inference with the Event Horizon Telescope II. The Zingularity framework for Bayesian artificial neural networks
• Search for the Epoch of Reionisation with HERA: Upper Limits on the Closure Phase Delay Power Spectrum
• Robust analysis of differential Faraday Rotation based on interferometric closure observables
• Interferometric Image Reconstruction using Closure Invariants and Machine Learning
• GALLIFRAY -- A geometric modeling and parameter estimation framework for black hole images using bayesian techniques
• Probing circular polarization and magnetic field structure in AGN
• Very-Long Baseline Interferometry Imaging with Closure Invariants using Conditional Image Diffusion
• A revised view of the linear polarization in the subparsec core of M87 at 7 mm
• An Introduction to Single-Antenna Radio Astronomical Polarimetry