On the principle of Astrometric Gravitational Wave Antenna

TL;DR

This paper proposes a novel space-based astrometric gravitational wave detector that uses precise measurements of stellar positions to detect and locate gravitational waves, complementing existing interferometer methods.

Contribution

It introduces a new concept for gravitational wave detection using astrometric measurements of star pairs, enhancing directional sensitivity and reducing modeling complexities.

Findings

Conceptual framework for astrometric GW detection

Potential for improved source localization

Complementary to existing interferometer detectors

Abstract

The direct detection of gravitational waves by ground-based optical interferometers has opened a new window in astronomy. Nevertheless, as these detectors are a combination of two Michelson-Morley like baselines, their sensitivity for determining the incident direction of a gravitational wave is quite weak compared to current high-precision of space astrometry. We therefore present a novel concept for a gravitational wave antenna in space that uses close pairs of point-like sources as natural sensors to record and characterize the very tiny variations in angular separations induced by a passing gravitational wave, thus operating complementarily to linear arm detectors and enabling to gain informations on the gravitational wave incoming direction. Indeed, the proposed astrometric gravitational wave observable builds on methods of relativistic astrometry that can substantially enhance the strength of gravitational wave signals by exploiting to the fullest the telescope optical resolution and, at same time, provide a powerful tool for identifying the direction to the sources that originated the gravitational wave by monitoring close pairs of stars. Furthermore, the use of two local-line-of-sights in a differential formulation avoids issues related to high order modeling of the local (Solar System) background geometry and the need for accurate satellite ephemeris and attitude.