Constraining the EdGB theory with extreme mass-ratio inspirals

Abstract

Abstract The Einstein-dilaton-Gauss–Bonnet (EdGB) theory is a modified theory of gravity which include a scalar field to couple with the higher order curvature terms. It has already been constrained with various observations include the gravitational wave (GW) with LIGO, Virgo and KAGRA (LVK) Collaboration. In this work, we study the capability for space-borne GW detectors to constrain the EdGB theory using the signal of Extreme Mass-Ratio Inspiral (EMRIs). We use the “numerical kludge (NK)” method to construct the waveform of EMRI in the EdGB theory, focusing on the case when the central black hole is spinless. We then study how a future space-borne gravitational wave detector, TianQin, for example, can place constraints on the EdGB theory through the detection of EMRIs. With the analysis using mismatch and Fisher Information Matrix (FIM), we find that the EdGB parameter $$\sqrt{\alpha }$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>α</mml:mi> </mml:msqrt> </mml:math> is expected to be constrained to the level of $$\sim \mathcal {O}(0.1)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>∼</mml:mo> <mml:mi>O</mml:mi> <mml:mo>(</mml:mo> <mml:mn>0.1</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> km.