Degeneracy measures for the algebraic classification of numerical spacetimes

Owen, Robert

doi:10.1103/physrevd.81.124042

Cited by 20 publications

(25 citation statements)

References 22 publications

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“…They determined the degeneracies between the PNDs by solving the eigenbivector problem and measuring the difference between eigenvalues. Their analysis found that the spacetime first numerically settled to type II, which has only one double PND, and then to type D. Owen [30] later showed that this measure was sensitive to the choice of tetrad used to compute the Weyl scalars needed to solve the characteristic equation. He proposed a new measure, less sensitive to the choice of tetrad, and showed that the spacetime settled to type D without first settling to type II.…”

Section: Overview and Historical Backgroundmentioning

confidence: 99%

“…These conditions are formulated in a fully covariant way and thus avoid the complications in [29,30] due to tetrad choice.…”

Section: Overview and Historical Backgroundmentioning

confidence: 99%

“…3 We use this set of algebraic and geometric conditions to provide a numerical measure of Kerrness. Previous studies have used multipole moments of the BH apparent horizon [26], horizon spin measurement comparisons [27], or Petrov classification [28][29][30] to characterize ringdown spacetimes. Our work is the first set of conditions that completely characterizes a spacetime as isometric to a Kerr manifold.…”

Section: Introductionmentioning

confidence: 99%

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On choosing the start time of binary black hole ringdowns

et al. 2018

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The final stage of a binary black hole merger is ringdown, in which the system is described by a Kerr black hole with quasinormal mode perturbations. It is far from straightforward to identify the time at which the ringdown begins. Yet determining this time is important for precision tests of the general theory of relativity that compare an observed signal with quasinormal mode descriptions of the ringdown, such as tests of the no-hair theorem. We present an algorithmic method to analyze the choice of ringdown start time in the observed waveform. This method is based on determining how close the strong field is to a Kerr black hole (Kerrness). Using numerical relativity simulations, we characterize the Kerrness of the strong-field region close to the black hole using a set of local, gauge-invariant geometric and algebraic conditions that measure local isometry to Kerr. We produce a map that associates each time in the gravitational waveform with a value of each of these Kerrness measures; this map is produced by following outgoing null characteristics from the strong and near-field regions to the wave zone. We perform this analysis on a numerical relativity simulation with parameters consistent with GW150914-the first gravitational-wave detection. We find that the choice of ringdown start time of 3 ms after merger used in the GW150914 study [B. P. Abbott et al. (Virgo Collaboration and LIGO Scientific Collaboration), Phys. Rev. Lett. 116, 221101 (2016).] to test general relativity corresponds to a high dimensionless perturbation amplitude of ∼7.5 × 10 −3 in the strong-field region. This suggests that in higher signal-to-noise detections, one would need to start analyzing the signal at a later time for studies that depend on the validity of black hole perturbation theory.

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Section: Overview and Historical Backgroundmentioning

confidence: 99%

“…These conditions are formulated in a fully covariant way and thus avoid the complications in [29,30] due to tetrad choice.…”

Section: Overview and Historical Backgroundmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On choosing the start time of binary black hole ringdowns

et al. 2018

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“…The choice of a consistent and suitable tetrad for NR continues to be explored [18,19]. Despite the ongoing challenges, a technique for computing the Weyl scalars has been successfully implemented and used for analysis where detailed comparison between waveforms was not necessary [20].…”

Section: Introductionmentioning

confidence: 99%

“…In the first case, the goal is to analyze curvature quantities at finite distances to provide information about the Petrov classification of the spacetime, test properties of perturbed Kerr black holes, probe regimes of strong gravity, etc. [14,[20][21][22][23][24]. In the second case, the goal is to analyze curvature quantities extrapolated or evolved to asymptotic null infinity to compute gravitational waveforms [25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Extending gravitational wave extraction using Weyl characteristic fields

et al. 2021

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We present a detailed methodology for extracting the full set of Newman-Penrose Weyl scalars from numerically generated spacetimes without requiring a tetrad that is completely orthonormal or perfectly aligned to the principal null directions. We also describe how to implement an extrapolation technique for computing the Weyl scalars' contribution at asymptotic null infinity in postprocessing. These methods have been used to produce Ψ 4 and h waveforms for the Simulating eXtreme Spacetimes (SXS) waveform catalog and now have been expanded to produce the entire set of Weyl scalars. These new waveform quantities are critical for the future of gravitational wave astronomy in order to understand the finiteamplitude gauge differences that can occur in numerical waveforms. We also present a new analysis of the accuracy of waveforms produced by the Spectral Einstein Code. While ultimately we expect Cauchy characteristic extraction to yield more accurate waveforms, the extraction techniques described here are far easier to implement and have already proven to be a viable way to produce production-level waveforms that can meet the demands of current gravitational-wave detectors.

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Seeking for toroidal event horizons from initially stationary BH configurations

Ponce¹,

Lousto²,

Zlochower³

2011

Class. Quantum Grav.

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Abstract. We construct and evolve non-rotating vacuum initial data with a ring singularity, based on a simple extension of the standard Brill-Lindquist multiple black-hole initial data, and search for event horizons with spatial slices that are toroidal when the ring radius is sufficiently large. While evolutions of the ring singularity are not numerically feasible for large radii, we find some evidence, based on configurations of multiple BHs arranged in a ring, that this configuration leads to singular limit where the horizon width has zero size, possibly indicating the presence of a naked singularity, when the radius of the ring is sufficiently large. This is in agreement with previous studies that have found that there is no apparent horizon surrounding the ring singularity when the ring's radius is larger than about twice its mass.

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Degeneracy measures for the algebraic classification of numerical spacetimes

Cited by 20 publications

References 22 publications

On choosing the start time of binary black hole ringdowns

On choosing the start time of binary black hole ringdowns

Extending gravitational wave extraction using Weyl characteristic fields

Seeking for toroidal event horizons from initially stationary BH configurations

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