CHRONOS: Cryogenic Gravitational Wave Detector Aims to Detect Intermediate-Mass Black Hole Mergers at Sub-Hz Frequencies

CHRONOS: China's Ambitious Gravitational Wave Detector Targets the 'Dark' Frequency Range

The CHRONOS project (Cryogenic sub-Hz cROss torsion bar detector with quantum NOn-demolition Speed meter) aims to detect gravitational waves from intermediate-mass black hole mergers in the challenging sub-Hz frequency range — a gap between LIGO and LISA.

The Detection Gap

Intermediate-mass black holes (IMBHs, ~10,000 solar masses) are the "missing link" between stellar and supermassive black holes. Their merger frequencies fall in the sub-Hz range, where seismic noise, radiation pressure noise, and thermal noise dominate.

CHRONOS Design

• Cryogenic operation — Reduces thermal noise
• Cross torsion bar — Novel mechanical design for sub-Hz sensitivity
• Quantum non-demolition speed meter — Pushes below standard quantum limit
• Target sensitivity — 10⁻¹⁸ Hz⁻¹/² at 2 Hz

Scientific Goals

1. Detect gravitational waves from IMBH mergers (~10⁴ solar masses)
2. Explore stochastic gravitational wave background
3. Test strong-field gravity
4. Probe black hole evolution

Why This Matters

1. Filling the frequency gap — CHRONOS would observe events invisible to both LIGO and LISA
2. Black hole evolution — IMBHs are key to understanding how supermassive black holes form
3. Quantum measurement — Quantum non-demolition techniques at macroscopic scales
4. Chinese leadership — Positions China at the frontier of gravitational wave astronomy