Advanced Virgo Plus for O5 -- Design Report Overview

TL;DR

The paper details the design and expected performance improvements of the Advanced Virgo Plus upgrades for the O5 gravitational wave observing run, focusing on stability, noise reduction, and sensitivity enhancements.

Contribution

It introduces new design solutions, including stable recycling cavities and subsystem renewals, to address previous limitations and improve detector performance.

Findings

Enhanced interferometer stability and sensitivity expected during O5.

Implementation of new vacuum, suspension, and optical systems.

Significant increase in astrophysical reach and scientific output.

Abstract

This document presents an overview of the design, implementation, and expected performance of the Advanced Virgo Plus (AdV+) upgrades in view of the O5 observing run. Following the experience gained during the O4 commissioning and operations, the Virgo Collaboration has revised the upgrade strategy to address limitations associated with marginally stable recycling cavities. The O5 upgrade program combines elements from the original AdV+ Phase II project with new design solutions, including the implementation of stable recycling cavities, a major modification to the central interferometer layout, and a comprehensive renewal of critical subsystems. The planned upgrades are organized in two steps, targeting progressive improvements in operational stability, noise reduction, and detector sensitivity. Key developments include new vacuum infrastructures, suspensions, mirrors, optical configurations, quantum noise reduction systems, and high-power laser technologies. The resulting configuration is expected to significantly enhance the interferometer performance, enabling a substantial increase in astrophysical reach and scientific return during O5.