Extending the micro-Hertz detection horizons via orbital resonance effect for geocentric gravitational wave antennas

TL;DR

This paper proposes a novel method for geocentric gravitational wave detectors to detect micro-Hertz signals by exploiting orbital resonance effects, significantly enhancing sensitivity and enabling new astrophysical observations.

Contribution

It introduces the concept of using orbital resonance effects to improve geocentric GW detector sensitivity in the micro-Hertz band, expanding detection capabilities without requiring long baselines.

Findings

Resonance effects induce orbital deviations that enhance sensitivity by 1-2 orders of magnitude.

Geocentric detectors can now detect SMBHBs across wider mass-redshift ranges.

Potential for joint GW and pulsar timing array observations for strong-field gravity tests.

Abstract

The $\mu$Hz gravitational wave band holds crucial insights into coalescing supermassive black hole binaries and stochastic backgrounds but remains inaccessible due to technical challenges. We demonstrate that geocentric space-based GW detectors (e.g., TianQin, gLISA, GADFLI) can bridge this gap by considering orbital resonance effects, circumventing the need for prohibitively long baselines. When GW frequencies match with integer multiples of a satellite's orbital frequency, sustained tidal forces induce cumulative orbital deviations through resonant effects, which, combined with orbital modulation, improve detector sensitivity by 1-2 orders of magnitude in the $\mu$Hz band. Consequently, geocentric missions can detect SMBHBs across significantly expanded mass-redshift parameter space. Crucially, such observations could synergize with pulsar timing array data of the same binaries at earlier inspiral stages, enabling unprecedented joint tests of strong-field gravity and binary evolution. Our findings establish geocentric antennas as a cost-effective, near-term precursor for unlocking the $\mu$Hz GW astronomy.