Speaker
Description
The Cherenkov Telescope Array Observatory (CTAO) is a new generation of telescope arrays for gamma-ray astronomy. The telescopes are designed to collect ultraviolet to red Cherenkov photons from extensive air showers with nanosecond sampling. The total mirror area of the telescopes exceeds that of the Extremely Large Telescope at each CTAO site: Paranal in the Atacama Desert (CTAO-South) and Roque de Los Muchachos in the Canary Islands (CTAO-North). The dozens of CTAO telescopes, their kilometer-long baselines, and their fast photodetection capabilities make the Observatory an exceptional optical instrument. In particular, fluctuations in the intensity of optical sources can be measured to perform interferometric measurements between pairs of telescopes through the Hanbury Brown and Twiss effect.
The Observatory's scientific applications in interferometric mode include generalizing cases opened up by its precursors (HESS, MAGIC, and VERITAS), such as measurements of the radii of massive stars, limb darkening, and the flattening of fast rotators. New and ambitious applications include observing stellar flares and spots and multiband imaging of exoplanet transits. Additionally, the CTAO interferometer could opportunistically characterize the geometry of high-energy photon emitters, such as nova flares in the Milky Way and supernovae in the Local Group.
The successful implementation of intensity interferometry on the CTAO precursors has shown that only modest adjustments are needed to fulfill the key requirements. The first set of minimal modifications to the arrays entails adding dedicated optical filters and signal samplers to the cameras, a high-bandwidth fiber optic network, additional White Rabbit nodes for synchronization, and the necessary infrastructure for data computation and storage. These adjustments would enable the CTAO to extend its observation time to include full moon periods, during which Cherenkov measurements are difficult. To achieve the most ambitious scientific objectives, a second phase would involve installing new interferometry-dedicated sensors in the cameras to increase the bandwidth and the number of channels per camera through spectral multiplexing.
This contribution presents the plan to enable intensity interferometry with the CTAO. Implementing interferometry on the CTAO offers enormous scientific possibilities, including those involving other optical telescopes at the Paranal and Roque sites.
