Testing general relativity with TianQin: the prospect of using the inspiral signals of black hole binaries

TL;DR

This study evaluates TianQin's potential to test general relativity using black hole binary inspiral signals across a wide mass range, demonstrating its competitive edge over other detectors in constraining modified gravity theories.

Contribution

The paper systematically assesses TianQin's capability to test various modified gravity theories via the parameterized post-Einsteinian waveform model, covering a broad mass and PN order range.

Findings

TianQin significantly improves constraints on ppE phase parameters compared to current ground-based detectors.

TianQin is competitive with future detectors like ET and LISA in specific mass and PN order regimes.

Detector networks involving TianQin can enhance constraints on theories like Chern-Simons and Gauss-Bonnet.

Abstract

In this paper, we carry out a systematic study of the prospect of testing general relativity with the inspiral signals of black hole binaries that could be detected with TianQin. The study is based on the parameterized post-Einsteinian (ppE) waveform, so that many modified gravity theories can be covered simultaneously. We consider black hole binaries with total masses ranging from $10\rm M_\odot\sim10^7 M_\odot$ and ppE corrections at post-Newtonian (PN) orders ranging from $-4$PN to $2$PN. Compared to the current ground-based detectors, TianQin can improve the constraints on the ppE phase parameter $\beta$ by orders of magnitude. For example, the improvement at the $-4$PN and $2$PN orders can be about $13$ and $3$ orders of magnitude (compared to the results from GW150914), respectively. Compared to future ground-based detectors, such as ET, TianQin is expected to be superior below the $-1$PN order, and for corrections above the $-0.5$PN order, TianQin is still competitive near the large mass end of the low mass range $[10 \rm M_\odot, \,10^3 \rm M_\odot]\,$. Compared to the future space-based detector LISA, TianQin can be competitive in the lower mass end as the PN order is increased. For example, at the $-4$PN order, LISA is always superior for sources more massive than about $30\rm M_\odot\,$, while at the $2$PN order, TianQin becomes competitive for sources less massive than about $10^4\rm M_\odot$. We also study the scientific potentials of detector networks involving TianQin, LISA and ET, and discuss the constraints on specific theories such as the dynamic Chern-Simons theory and the Einstein-dilaton Gauss-Bonnet theory.