Instrumental development for Cryogenic sub-Hz cROss torsion bar detector with quantum NOn-demolition Speed meter (CHRONOS)

TL;DR

CHRONOS is a proposed cryogenic torsion bar detector aiming to detect low-frequency gravitational waves from intermediate-mass black-hole mergers and stochastic backgrounds, utilizing advanced techniques for enhanced sensitivity.

Contribution

This paper introduces the design and commissioning status of CHRONOS, a novel low-frequency gravitational wave detector employing torsion bars, speed meters, and cryogenic mirrors.

Findings

Designed to reach strain sensitivity of 10^{-18} Hz^{-1/2} at 2 Hz

Demonstrated a Michelson interferometer as part of CHRONOS components

Aims to detect gravitational waves from IMBH mergers and stochastic backgrounds

Abstract

Gravitational waves from intermediate-mass black-hole (IMBH) binaries is a probe of strong-field gravity and black-hole evolution. Detection of IMBH is challenging because of their typically low frequency where the seismic noise, radiation pressure noise, and thermal noise dominate. The Cryogenic sub-Hz cROss torsion bar detector with quantum NOn-demolition Speed meter (CHRONOS) has been proposed to reach a strain sensitivity of $10^{-18} {\rm Hz}^{-1/2}$ at 2 Hz. It aims to detect GW from IMBH mergers with the mass of $\mathcal{O}(10^4)$ M$_{\odot}$ and to explore stochastic gravitational background of $\Omega_{\rm GW} \sim 2\times 10^{-3}$ at 2 Hz. We present the overview of the CHRONOS hardware which is designed to integrate key techniques for improving low frequency sensitivity; torsion bar, speed meter, and cryogenic mirror. As a demonstration of the interferometer operation, we also report the commissioning status of a Michelson interferometer in National Central University in Taiwan which has been assembled as a partial component of CHRONOS.