GRAVITY+ at the VLTI: instrumental advances enabling high-angular-resolution AGN science
Abstract
We present an overview of how recent and upcoming GRAVITY+ upgrades at the VLTI interconnect instrument and science, enabling high-angular-resolution studies of active galactic nuclei (AGN). Improvements such as wideangle off-axis fringe tracking, enhanced fringe-tracker performance, and state-of-the-art adaptive optics, including laser guide stars, increase sensitivity and sky coverage, allowing coherent observations of fainter targets. These instrumental advances directly support measurements of black hole masses out to high redhsift and spatially resolved studies of broad-line region structure and kinematics, as well as resolved observations of [O III] emission tracing the inner narrow-line region at z = 4. We also discuss prospects for supermassive black hole binary searches with GRAVITY+.