Black-hole ringdown as a probe of higher-curvature gravity theories

Abstract

Detecting gravitational waves from coalescing compact binaries allows us to explore the dynamical, nonlinear regime of general relativity and constrain modifications to it. Some of the gravitational-wave events observed by the LIGO-Virgo Collaboration have sufficiently high signal-to-noise ratio in the merger, allowing us to probe the relaxation of the remnant black hole to its final, stationary state -the so-called black-hole ringdown, which is characterized by a set of quasinormal modes. Can we use the ringdown to constrain deviations from general relativity, as predicted by several of its contenders? Here, we address this question by using an inspiralmerger-ringdown waveform model in the effective-one-body formalism, augmented with a parametrization of the ringdown based on an expansion in the final black hole's spin. We give a prescription on how to include in this waveform model, the quasinormal mode frequencies calculated on a theory-by-theory basis. In particular, we focus on theories that modify general relativity by higher-order curvature corrections, namely, Einsteindilaton-Gauss-Bonnet, dynamical Chern-Simons theories, and cubic-and quartic-order effective-field-theories of general relativity. We use this parametrized waveform model to measure the ringdown properties of the two loudests ringdown signals observed so far, GW150914 and GW200129. We find that while the Einstein-dilaton-Gauss-Bonnet theory cannot be constrained with these events, we can place upper bounds on the fundamental length-scale of cubic-( cEFT 38.2 km) and quartic-order ( qEFT 51.3 km) effective-field-theories of general relativity, and of dynamical Chern-Simons gravity ( dCS 38.7 km). The latter result is a concrete example of a theory presently unconstrained by inspiral-only analyses which, however, can be constrained by merger-ringdown studies with current gravitational-wave data.

Collective filters: a new approach to analyze the gravitational-wave ringdown of binary black-hole mergers

“…Later on, a lot of effort has been made to investigate BH spectroscopy under different scenarios [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. In particular, the studies by Cardoso et al [10,42,43], Foit et al [44] and Laghi et al [45] implied that QNMs could reflect the quantum nature of BHs or other exotic compact objects (ECOs); hence one can use this fact to test GR and constrain modified gravity [46][47][48][49]. Since the detection of GW150914 [50], BH spectroscopy with real observational data has became available.…”

Repeating Fast Radio Bursts from Neutron Star Binaries: Multi-band and Multi-messenger Opportunities

“…Projected bounds on the coupling constant √ α in dCS gravity using Q-Love or Q-C universal relation. These bounds are stronger than the existing bounds from solar system experiments [100], table-top experiments [101], GWs [102], and multimessenger observations [95].…”

Causality constraints on black holes beyond GR

“…There are many other interesting signatures associated with the operators that we expect to be present in the scalar-GB EFT. The phenomenology of cubic and quartic curvature operators have been discussed in [69][70][71][72][73] and [45][46][47]73], respectively. Besides modifications of the Schwarzschild (and Kerr) geometries, these include deviations from GR at the leading order in QNMs, quadrupole moments, non-vanishing Love numbers, and corrections to the gravitational-wave signals at relatively high post-Newtonian (PN) order.…”