Testing Gravity with Quasi Periodic Oscillations from accreting Black Holes: the Case of Einstein-Dilaton-Gauss-Bonnet Theory

TL;DR

Future high-precision X-ray observations of QPOs from accreting black holes can test Einstein-Dilaton-Gauss-Bonnet gravity, potentially constraining deviations from general relativity in the strong-field regime.

Contribution

This paper demonstrates how QPO measurements can be used to test and constrain Einstein-Dilaton-Gauss-Bonnet gravity using upcoming X-ray missions.

Findings

QPO frequencies can distinguish between GR and alternative theories.

LOFT mission could set the tightest constraints on Einstein-Dilaton-Gauss-Bonnet theory.

Strong-field deviations from GR can be probed with future X-ray data.

Abstract

Quasi-Periodic Oscillations (QPOs) observed in the X-ray flux emitted by accreting black holes, are associated to phenomena occurring near the horizon. Future very large area X-ray instruments will be able to measure QPO frequencies with very high precision, thus probing this strong-field region. By using the relativistic precession model, we show the way in which QPO frequencies could be used to test general relativity against those alternative theories of gravity which predict deviations from the classical theory in the strong-field regime. We consider one of the best motivated strong-curvature corrections to general relativity, namely the Einstein-Dilaton-Gauss-Bonnet theory, and show that a detection of QPOs with the expected sensitivity of the proposed ESA M-class mission LOFT would set the most stringent constraints on the parameter space of this theory.