Optical intensity interferometry observations using the MAGIC imaging atmospheric Cherenkov telescopes

TL;DR

This paper demonstrates that existing Imaging Atmospheric Cherenkov Telescopes can be used for optical intensity interferometry, achieving microarcsecond resolution and significantly improving sensitivity over past experiments.

Contribution

It introduces a simple optical setup on MAGIC telescopes for optical interferometry, enabling high-resolution observations of stars with enhanced sensitivity.

Findings

Detected coherent photon intensity fluctuations for three stars.

Achieved sensitivity roughly 10 times better than the 1970s Narrabri interferometer.

Revealed potential for high-resolution optical astronomy using IACTs.

Abstract

Imaging Atmospheric Cherenkov Telescopes (IACTs) currently in operation feature large mirrors and order of 1 ns time response to signals of a few photo-electrons produced by optical photons. This means that they are ideally suited for optical interferometry observations. Thanks to their sensitivity to visible wavelengths and long baselines optical intensity interferometry with IACTs allows reaching angular resolutions of tens to microarcsec. We have installed a simple optical setup on top of the cameras of the two 17 m diameter MAGIC IACTs and observed coherent fluctuations in the photon intensity measured at the two telescopes for three different stars. The sensitivity is roughly 10 times better than that achieved in the 1970s with the Narrabri interferometer.