Speaker
Description
Gravitational-wave ringdowns encode the characteristic oscillation spectrum of the compact remnant and provide a direct probe of strong-field gravity. Yet conventional analyses usually infer remnant properties with theory-specific waveform templates, entangling the information extracted from the data with the assumed model. Ringdown inference is also often treated in isolation, leaving aside valuable pre-merger information about the progenitor binary and, consequently, the expected excitation of the remnant modes.
We present SPRING (short for Spectral-level Pre-merger-informed RINGdown inference), a framework that separates data-driven spectral inference from theory-specific interpretation. The ringdown signal is first used to reconstruct the observable mode spectrum without assuming a theoretical model. Information from the pre-merger signal is then used to guide the expected mode excitation. SPRING also retains the full joint spectral likelihood, including correlations between the mode spectral parameters, rather than relying only on low-dimensional marginalized posteriors. The same spectral likelihood can then be tested against Kerr and beyond-Kerr predictions.
This viewpoint also suggests a geometric interpretation: each theoretical model defines a lower-dimensional manifold in the observable spectral space, and the theory-agnostic information extracted from the ringdown signal can be compared directly with the corresponding manifolds. Such a formulation may make parameter degeneracies and deviations that can be partially absorbed by shifts in remnant parameters more transparent. We illustrate the framework using GW250114 and controlled injections, and discuss its potential as a common interface between gravitational-wave observations, black-hole spectroscopy, and fundamental theories of compact objects.