Speaker
Description
Intensity interferometry in the optical band has experienced a notable resurgence, largely driven by the adaptation of Cherenkov telescope arrays designed for gamma-ray astronomy. This contribution explores the scientific potential of the thousands of baselines and kilometre-scale extent of the Cherenkov Telescope Array Observatory (CTAO) as an optical interferometer, as well as the technical adaptations required to operate in this mode during nights around full moon. We review a variety of relevant scientific applications, ranging from the study of hot stars to the measurement of the geometry of non-thermal emitters. We simulate the expected performance of the CTAO intensity interferometer by considering a two-stage deployment of interferometric techniques. The first stage involves minor camera adaptations and the installation of dedicated correlators in the on-site data processing centres. Nearly a thousand hot stars will become accessible for precision measurements, with performance at the shortest optical wavelengths comparable to the best amplitude interferometers operating at longer wavelengths. The second stage requires the integration of ultra-fast photodetectors with dedicated optics to enable simultaneous observations in several narrow bands. The target sample will then exceed ten thousand stars, including over a hundred solar-type stars. It will become possible to reconstruct images of photospheres with an unprecedented resolution of tens of microarcsecond in a largely unexplored range of the optical spectrum. The technical constraints associated with interferometric observations entail negligible costs for the first stage compared to the observatory itself, while extending the operational cycle of the CTAO to periods when gamma-ray observations are challenging. In addition to its competitive sensitivity and unprecedented resolution, the second stage implementation would pave the way for the CTAO to be interconnected to major optical observatories on site, offering revolutionary observational potential.
