Description
Abstract: Gravitational waves from coalescing compact binaries provide a unique
opportunity to test General Relativity (GR) in the highly dynamical, strong-field
regime. So far, most tests of GR with gravitational-wave signals have followed
parametrized, theory-independent approaches. An alternative avenue consists in
developing inspiral-merger-ringdown (IMR) waveform models in specific beyond-
GR theories by combining analytical and numerical-relativity results. In this talk,
we focus on Einstein-scalar-Gauss-Bonnet (ESGB) gravity, a theory which has
attracted particular attention due to its rich phenomenology for binary black-hole
mergers arising from nontrivial scalar fields. We discuss how to include ESGB
corrections to the resummed gravitational wave modes and energy fluxes for
quasicircular binaries within the effective-one-body (EOB) formalism. Key
modifications from GR include: (1) ESGB corrections to the metric modes through
2PN order, resummed using a factorization scheme inspired by GR; (2) an
additional scalar flux entering at relative -1PN order (dipolar radiation) and
extending through 2.5PN order. We also briefly discuss ESGB corrections to the
conservative dynamics (3PN Hamiltonian) and merger-ringdown waveform (quasinormal-
mode frequencies and remnant mass and spin). Combining these
ingredients, we provide the first complete IMR waveform model in a beyond-GR
theory and discuss the resulting waveform phenomenology. Finally, we present
constraints on the fundamental ESGB coupling from recent gravitational-wave
observations.
