Phase Closure Image Reconstruction for Future VLTI Instrumentation

TL;DR

This study evaluates the potential of next-generation optical interferometers, specifically VLTI with six telescopes, to produce high-resolution images of astronomical sources, demonstrating significant improvements over current capabilities.

Contribution

It provides an analysis of how the number of telescopes and observation strategies influence image reconstruction quality for future VLTI instruments.

Findings

Six telescopes during one night optimize image quality.

A 200-meter baseline achieves 4 mas resolution, comparable to ALMA.

The proposed setup can image complex stellar surfaces and microlensing events.

Abstract

Classically, optical and near-infrared interferometry have relied on closure phase techniques to produce images. Such techniques allow us to achieve modest dynamic ranges. In order to test the feasibility of next generation optical interferometers in the context of the VLTI-spectro-imager (VSI), we have embarked on a study of image reconstruction and analysis. Our main aim was to test the influence of the number of telescopes, observing nights and distribution of the visibility points on the quality of the reconstructed images. Our results show that observations using six Auxiliary Telescopes (ATs) during one complete night yield the best results in general and is critical in most science cases; the number of telescopes is the determining factor in the image reconstruction outcome. In terms of imaging capabilities, an optical, six telescope VLTI-type configuration and ~200 meter baseline will achieve 4 mas spatial resolution, which is comparable to ALMA and almost 50 times better than JWST will achieve at 2.2 microns. Our results show that such an instrument will be capable of imaging, with unprecedented detail, a plethora of sources, ranging from complex stellar surfaces to microlensing events.