Spin-orbit effects for compact binaries in scalar-tensor gravity - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue JCAP Année : 2021

Spin-orbit effects for compact binaries in scalar-tensor gravity

Résumé

Gravitational waves provide us with a new window into our Universe, and have already been used to place strong constrains on the existence of light scalar fields, which are a common feature in many alternative theories of gravity. However, spin effects are still relatively unexplored in this context. In this work, we construct an effective point-particle action for a generic spinning body that can couple both conformally and disformally to a real scalar field, and we show that requiring the existence of a self-consistent solution automatically implies that if a scalar couples to the mass of a body, then it must also couple to its spin. We then use well-established effective field theory techniques to conduct a comprehensive study of spin-orbit effects in binary systems to leading order in the post-Newtonian (PN) expansion. Focusing on quasicircular nonprecessing binaries for simplicity, we systematically compute all key quantities, including the conservative potential, the orbital binding energy, the radiated power, and the gravitational-wave phase. We show that depending on how strongly each member of the binary couples to the scalar, the spin-orbit effects that are due to a conformal coupling first enter into the phase at either 0.5 PN or 1.5 PN order, while those that arise from a disformal coupling start at either 3.5 PN or 4.5 PN order. This suppression by additional PN orders notwithstanding, we find that the disformal spin-orbit terms can actually dominate over their conformal counterparts due to an enhancement by a large prefactor. Accordingly, our results suggest that upcoming gravitational-wave detectors could be sensitive to disformal spin-orbit effects in double neutron star binaries if at least one of the two bodies is sufficiently scalarised.

Dates et versions

hal-03315940 , version 1 (06-08-2021)

Identifiants

Citer

Philippe Brax, Anne-Christine Davis, Scott Melville, Leong Khim Wong. Spin-orbit effects for compact binaries in scalar-tensor gravity. JCAP, 2021, 10, pp.075. ⟨10.1088/1475-7516/2021/10/075⟩. ⟨hal-03315940⟩
26 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Mastodon Facebook X LinkedIn More