Gravitational-wave echoes from numerical-relativity waveforms via spacetime construction near merging compact objects
Bibliographic record
Abstract
We propose a new approach toward reconstructing the late-time near-horizon geometry of merging binary black holes, and toward computing gravitational-wave echoes from exotic compact objects. A binary black-hole merger spacetime can be divided by a timelike hypersurface into a black-hole perturbation (BHP) region (in which the spacetime geometry can be approximated by homogeneous linear perturbations of the final Kerr black hole) and a nonlinear region. At late times, the boundary between the two regions is an infalling shell. The BHP region contains late-time gravitational waves emitted toward the future horizon, as well as those emitted toward future null infinity. In this region, by imposing no-ingoing-wave conditions at past null infinity and matching outgoing waves at future null infinity with waveforms computed from numerical relativity, we can obtain waves that travel toward the future horizon. In particular, the Newman-Penrose ${\ensuremath{\psi}}_{0}$ associated with the ingoing wave on the horizon is related to tidal deformations measured by fiducial observers floating above the horizon. We further determine the boundary of the BHP region on the future horizon by imposing that ${\ensuremath{\psi}}_{0}$ inside the BHP region can be faithfully represented by quasinormal modes. Using a physically motivated method to impose boundary conditions near the horizon and applying the so-called Boltzmann reflectivity, we compute the quasinormal modes of nonrotating exotic compact objects, as well as gravitational-wave echoes. We also investigate the detectability of these echoes in current and future detectors and prospects for parameter estimation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".