Combining underground and on-surface third-generation gravitational-wave interferometers

TL;DR

This paper compares the performance of various configurations of third-generation gravitational-wave detectors, including underground and surface L-shaped interferometers, and assesses their combined capabilities in European and intercontinental networks.

Contribution

It introduces and evaluates a novel network configuration combining underground and surface third-generation GW detectors, expanding on previous designs.

Findings

Underground and surface detector networks have comparable sensitivities.

European and intercontinental networks enhance detection capabilities.

The proposed configurations improve sky localization and parameter estimation.

Abstract

Recently, detailed studies have been made to compare the performance of the European next generation GW observatory Einstein Telescope (ET) in a single-site triangular configuration with the performance of a configuration featuring two L-shaped detectors in different sites, still taken to have all other ET characteristics except for the geometry, in particular, underground and composed of a low-frequency interferometer working at cryogenic temperatures and a high-frequency interferometer working at room temperature. Here we study a further possibility for a European network, made by a single L-shaped underground detector, like one of the detectors considered for the 2L version of ET, and a single third-generation 20-km L-shaped interferometer on the surface. We compare the performances of such a network to those of the triangle and of the 2L-underground ET configurations. We then examine the performance of an intercontinental network made by a 40-km CE in the US, together with any of these European networks.