Fortifying gravitational-wave tests of general relativity against astrophysical assumptions

Tests of general relativity with gravitational-wave sources often rely on inferring both the degree to which the signal deviates from general relativity and the astrophysical properties of the source. Due to the nature of the gravitational-wave signal, the inferred deviations and astrophysical parameters can be highly correlated. As a consequence, prior assumptions about the astrophysical population impact the inferred deviation. Therefore, information about the underlying astrophysical population must be jointly inferred within these tests of general relativity to avoid biases. In this study, we present a framework to mitigate these biases and directly apply the method to constrain the graviton mass and post-Newtonian deviations from binary black hole mergers observed by the LIGO-Virgo-KAGRA Collaboration.