Advanced Virgo during the LIGO-Virgo-KAGRA fourth observing run
arXiv:2607.26872
The paper reports on Advanced Virgo's participation in the fourth observing run (O4) of the global gravitational‑wave detector network, describing the commissioning of its new signal‑recycling optical configuration and other upgrades, and presenting its operational performance.
Abstract
From April 10, 2024 to November 18, 2025 Advanced Virgo participated in the fourth observing run of the network of gravitational-wave detectors, together with Advanced LIGO and KAGRA. For this observing run Advanced Virgo has completed its design optical configuration with the installation of a signal recycling mirror. In this paper we describe the challenges encountered in commissioning this optical configuration, alongside the other upgrades performed between the third and fourth observing run. The Virgo detector operated with a 68.9% duty cycle and with an angle-averaged median range to binary neutron star mergers of 53 Mpc.
54 pages, 21 figures