Spin-orbit effects for compact binaries in scalar-tensor gravity
Authors
Brax, P
Davis, AC
Melville, S
Wong, LK
Publication Date
2021Journal Title
Journal of Cosmology and Astroparticle Physics
ISSN
1475-7516
Publisher
IOP Publishing
Volume
2021
Issue
10
Language
en
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
Brax, P., Davis, A., Melville, S., & Wong, L. (2021). Spin-orbit effects for compact binaries in scalar-tensor gravity. Journal of Cosmology and Astroparticle Physics, 2021 (10) https://doi.org/10.1088/1475-7516/2021/10/075
Abstract
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 0.5PN or 1.5PN order, while those that arise from a
disformal coupling start at either 3.5PN or 4.5PN 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.
Keywords
Gravitational waves in GR and beyond : theory, dark energy theory, modified, gravity
Sponsorship
EPSRC (EP/T017481/1)
Identifiers
jcap_108p_0721, jcap_108p_0721
External DOI: https://doi.org/10.1088/1475-7516/2021/10/075
This record's URL: https://www.repository.cam.ac.uk/handle/1810/329903
Rights
Licence:
http://creativecommons.org/licenses/by/4.0/
Statistics
Total file downloads (since January 2020). For more information on metrics see the
IRUS guide.
Recommended or similar items
The current recommendation prototype on the Apollo Repository will be turned off on 03 February 2023. Although the pilot has been fruitful for both parties, the service provider IKVA is focusing on horizon scanning products and so the recommender service can no longer be supported. We recognise the importance of recommender services in supporting research discovery and are evaluating offerings from other service providers. If you would like to offer feedback on this decision please contact us on: support@repository.cam.ac.uk