Probing Supermassive Black Hole Binaries with Orbital Resonances of Laser-Ranged Satellite

TL;DR

This paper proposes using satellite laser ranging (SLR) to detect gravitational wave-induced resonances from coalescing supermassive black hole binaries, offering a feasible method before space-based GW detectors become operational.

Contribution

It introduces a novel approach of probing SMBHBs through SLR-induced resonant effects, analyzing detection thresholds and potential for early detection using existing and future SLR data.

Findings

Resonant effects can be detected within redshift z~1 with current SLR precision in 1-2 years.

Improved ranging precision reduces detection time to months.

Joint SLR missions enhance detection confidence and SNR.

Abstract

Coalescing supermassive black hole binaries (SMBHBs) are the primary source candidates for low frequency gravitational wave (GW) detections, which could bring us deep insights into galaxy evolutions over cosmic time and violent processes of spacetime dynamics. Promising candidates had been found based on optical and X-ray observations, which claims for new and ready-to-use GW detection approaches before the operations of space-borne antennas. We show that, satellite laser ranging (SLR) missions could serve as probes of coalescing SMBHBs through the GW-induced resonant effects. Lasting and characteristic imprints caused by such resonances in the residual distances or accelerations from SLR measurements are studied, and the detection SNR is analyzed with both the current and future improved ranging precisions. Within redshift $z \sim 1$, the threshold SNR=5 requires 1-2 years of accumulated data for the current precision and months of data for improved precision, which are workable for the data processing of SLR missions. Meanwhile, joint detections with multiple SLR missions could further improve the total SNR and the confidence level. Such a detection scheme could fulfill the requirement of a tentative SMBHB probe during the preparing stage of LISA and Taiji, and it requires no further investment to any new and advanced facilities. It is also worthwhile to look back and re-process the archived data from the past decades, in where resonant signals from SMBHBs might be hidden.