Ground Based Low-Frequency Gravitational-wave Detector With Multiple Outputs

TL;DR

This paper introduces a new gravitational-wave detector, TOBA, with multiple outputs that enhances detection capabilities and parameter estimation by monitoring different rotational degrees of freedom, achieving stable operation and improved sensitivity.

Contribution

The paper presents the development and successful operation of a multi-output gravitational-wave detector with improved sensitivity and data stability, enabling better source characterization.

Findings

Stable continuous operation over 24 hours.

Sensitivity improved to 1e-10 Hz^{-1/2} at 3 Hz for one output.

Multiple outputs provide diverse information for GW detection.

Abstract

We have developed a new gravitaional-wave (GW) detector, TOrsion-Bar Antenna (TOBA), with multiple-output configuration. TOBA is a detector with bar-shaped test masses that rotate by the tidal force of the GWs. In our detector, three independent information about the GW signals can be derived by monitoring multiple rotational degrees of freedom, i.e., horizontal rotations and vertical rotations of the bars. Since the three outputs have different antenna pattern functions, the multi-output system improves the detection rate and the parameter estimation accuracy. It is effective in order to obtain further details of the GW sources, such as population and directions. We successfully operated the multi-output detector continuously for more than 24 hours with stable data quality. Also, the sensitivity of one of the signals is improved to be $1 \times 10^{-10}$ ${\rm Hz}^{-1/2}$ at 3 Hz by the combination of the passive and active vibration isolation systems, while sensitivities to possible GW signals derived from the vertical rotations are worse than that from the horizontal rotation.