Browsing by Author "Nair, Remya"

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Fundamental physics implications on higher-curvature theories from the binary black hole signals in the LIGO-Virgo Catalog GWTC-1
(2020-04) Nair, Remya; Perkins, Scott; Silva, Hector O.; Yunes, Nico
Gravitational-wave astronomy oﬀers not only new vistas into the realm of astrophysics, but it also opens an avenue for probing, for the ﬁrst time, general relativity in its strong-ﬁeld, nonlinear, and dynamical regime, where the theory’s predictions manifest themselves in their full glory. We present a study of whether the gravitational-wave events detected so far by the LIGO-Virgo scientiﬁc collaborations can be used to probe higher-curvature corrections to general relativity. In particular, we focus on two examples: Einstein-dilaton-Gauss-Bonnet and dynamical Chern-Simons gravity. We ﬁnd that the two events with a low-mass m ≈ 7M⊙ BH (GW151226 and GW170608) place stringent constraints on Einstein-dilaton-Gauss-Bonnet gravity, α1/2 . 5.6 km, whereas EdGB dynamical Chern-Simons gravity remains unconstrained by the gravitational-wave observations analyzed.
Improved binary pulsar constraints on the parametrized post-Einsteinian framework
(American Physical Society, 2020-05) Nair, Remya; Yunes, Nicolás
The parametrized post-Einsteinian formalism was developed to search for generic deviations from general relativity with gravitational waves. We here present constraints on this framework using Bayesian analysis of a set of binary pulsar observations. In particular, we use measurements of the Keplerian and post-Keplerian parameters of six different binary pulsar systems, and Markov-Chain Monte-Carlo exploration to calculate posteriors on the parametrized post-Einsteinian parameters and derive robust constraints. We find improvements of 1–2 orders of magnitude in the strength of constraints when combining all six observations, relative to what one can achieve when using only the double binary pulsar. We also find that the constraints are robust to any correlation with the binary’s component masses. The bounds on the parametrized post-Einsteinian framework derived here could be used as a prior in future Bayesian tests of general relativity with gravitational wave observations.
Improved gravitational-wave constraints on higher-order curvature theories of gravity
(American Physical Society, 2021-07) Perkins, Scott E.; Nair, Remya; Silva, Hector O.; Yunes, Nicolás
Gravitational wave observations of compact binaries allow us to test general relativity (and modifications thereof) in the strong and highly dynamical field regime of gravity. Here, we confront two extensions to general relativity, dynamical Chern-Simons, and Einstein-dilaton-Gauss-Bonnet theories, against the gravitational wave sources from the GWTC-1 and GWTC-2 catalogs by the LIGO-Virgo Collaboration. By stacking the posterior of individual events, we strengthen the constraint on the square root of the coupling parameter in Einstein-dilaton-Gauss-Bonnet gravity to √αEdGB<1.7 km, but we are unable to place meaningful constraints on dynamical Chern-Simons gravity. Importantly, we also show that our bounds are robust to (i) the choice of general-relativity base waveform model, upon which we add modifications, (ii) unknown higher post-Newtonian order terms in the modifications to general relativity, (iii) the small-coupling approximation, and (iv) uncertainties on the nature of the constituent compact objects.