A Xylophone Configuration for a third Generation Gravitational Wave Detector

TL;DR

This paper proposes a two-band xylophone configuration for third-generation gravitational wave detectors, combining high-power and cryogenic interferometers to enhance sensitivity across a broad frequency range.

Contribution

It introduces a novel 2-band xylophone design that addresses thermal and quantum noise challenges in advanced GW observatories.

Findings

Inspiral range of 3200 Mpc for neutron stars

Inspiral range of 38000 Mpc for black holes

Significantly improved sensitivity over single broadband designs

Abstract

Achieving the demanding sensitivity and bandwidth, envisaged for third generation gravitational wave (GW) observatories, is extremely challenging with a single broadband interferometer. Very high optical powers (Megawatts) are required to reduce the quantum noise contribution at high frequencies, while the interferometer mirrors have to be cooled to cryogenic temperatures in order to reduce thermal noise sources at low frequencies. To resolve this potential conflict of cryogenic test masses with high thermal load, we present a conceptual design for a 2-band xylophone configuration for a third generation GW observatory, composed of a high-power, high-frequency interferometer and a cryogenic low-power, low-frequency instrument. Featuring inspiral ranges of 3200Mpc and 38000Mpc for binary neutron stars and binary black holes coalesences, respectively, we find that the potential sensitivity of xylophone configurations can be significantly wider and better than what is possible in a single broadband interferometer.