William Throwe
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View article: Late-Time Tails in Nonlinear Evolutions of Merging Black Holes
Late-Time Tails in Nonlinear Evolutions of Merging Black Holes Open
We uncover late-time gravitational-wave tails in fully nonlinear 3+1 dimensional numerical relativity simulations of merging black holes, using the highly accurate p code. We achieve this result by exploiting the strong magnification of la…
View article: Error quantification and comparison of binary neutron star gravitational waveforms from numerical relativity codes
Error quantification and comparison of binary neutron star gravitational waveforms from numerical relativity codes Open
Future gravitational wave detections of merging binary neutron star systems have the possibility to tightly constrain the equation of state of dense nuclear matter. In order to extract such constraints, gravitational waveform models need t…
View article: The SXS collaboration’s third catalog of binary black hole simulations
The SXS collaboration’s third catalog of binary black hole simulations Open
We present a major update to the Simulating eXtreme Spacetimes (SXSs) Collaboration’s catalog of binary black hole (BBH) simulations. Using highly efficient spectral methods implemented in the Spectral Einstein Code ( SpEC ), we have nearl…
Horizon tracking for asynchronous parallel black hole simulations Open
In the field of gravitational wave science, next-generation detectors will be substantially more accurate than the current suite of detectors. Numerical relativity simulations of binary black hole (BBH) gravitational waveforms must become …
View article: Modeling the BMS transformation induced by a binary black hole merger
Modeling the BMS transformation induced by a binary black hole merger Open
Understanding the characteristics of the remnant black hole formed in a binary black hole merger is crucial for conducting gravitational wave astronomy. Typically, models of remnant black holes provide information about their mass, spin, a…
View article: Robustness of extracting quasinormal mode information from black hole merger simulations
Robustness of extracting quasinormal mode information from black hole merger simulations Open
In linear perturbation theory, the ringdown of a gravitational wave (GW) signal is described by a linear combination of quasinormal modes (QNMs). Detecting QNMs from GW signals is a promising way to test GR, central to the developing field…
View article: Merging black holes with Cauchy-characteristic matching: Computation of late-time tails
Merging black holes with Cauchy-characteristic matching: Computation of late-time tails Open
Cauchy-characteristic matching (CCM) is a numerical-relativity technique that solves Einstein's equations on an effectively infinite computational domain, thereby eliminating systematic errors associated with artificial boundary conditions…
Relieving Scale Disparity in Binary Black Hole Simulations Open
is a method of reducing computational burden in numerical relativity simulations of binary black holes in situations where there is a good analytical model of the geometry around (one or both of) the objects. Two such scenarios of relevanc…
Relieving Scale Disparity in Binary Black Hole Simulations Open
is a method of reducing computational burden in numerical relativity simulations of binary black holes in situations where there is a good analytical model of the geometry around (one or both of) the objects. Two such scenarios of relevanc…
View article: Echoes from beyond: Detecting gravitational-wave quantum imprints with LISA
Echoes from beyond: Detecting gravitational-wave quantum imprints with LISA Open
We assess the prospects for detecting gravitational wave echoes arising due to the quantum nature of black hole horizons with LISA. In a recent proposal, Bekenstein's black hole area quantization is connected to a discrete absorption spect…
Signatures from metastable oppositely-charged black hole binaries in scalar Gauss-Bonnet gravity Open
We conduct numerical simulations of inspiraling, oppositely-charged black holes in the class of scalar-Gauss-Bonnet theories that exhibit spontaneous black hole scalarization. For quasi-circular, equal-mass binaries near the existence thre…
View article: Probing the ringdown perturbation in binary black hole coalescences with an improved quasi-normal mode extraction algorithm
Probing the ringdown perturbation in binary black hole coalescences with an improved quasi-normal mode extraction algorithm Open
Using gravitational waves to probe the geometry of the ringing remnant black hole formed in a binary black hole coalescence is a well-established way to test Einstein's theory of general relativity. However, doing so requires knowledge of …
View article: Simulating binary black hole mergers using discontinuous Galerkin methods
Simulating binary black hole mergers using discontinuous Galerkin methods Open
Binary black holes are the most abundant source of gravitational-wave observations. Gravitational-wave observatories in the next decade will require tremendous increases in the accuracy of numerical waveforms modeling binary black holes, c…
View article: Late-time tails in nonlinear evolutions of merging black holes
Late-time tails in nonlinear evolutions of merging black holes Open
We uncover late-time gravitational-wave tails in fully nonlinear 3+1 dimensional numerical relativity simulations of merging black holes, using the highly accurate SpEC code. We achieve this result by exploiting the strong magnification of…
View article: Overtones and Nonlinearities in Binary Black Hole Ringdowns
Overtones and Nonlinearities in Binary Black Hole Ringdowns Open
Using high-accuracy numerical relativity waveforms, we confirm the presence of numerous overtones of the $\ell=2$, $m=2$ quasinormal mode early in the ringdown of binary black hole mergers. We do this by demonstrating the stability of the …
View article: Binary neutron star mergers using a discontinuous Galerkin-finite difference hybrid method
Binary neutron star mergers using a discontinuous Galerkin-finite difference hybrid method Open
We present a discontinuous Galerkin-finite difference hybrid scheme that allows high-order shock capturing with the discontinuous Galerkin method for general relativistic magnetohydrodynamics in dynamical spacetimes. We present several opt…
View article: A review of gravitational memory and BMS frame fixing in numerical relativity
A review of gravitational memory and BMS frame fixing in numerical relativity Open
Gravitational memory effects and the BMS freedoms exhibited at future null infinity have recently been resolved and utilized in numerical relativity simulations. With this, gravitational wave models and our understanding of the fundamental…
View article: Simulating binary black hole mergers using discontinuous Galerkin methods
Simulating binary black hole mergers using discontinuous Galerkin methods Open
Binary black holes are the most abundant source of gravitational-wave observations. Gravitational-wave observatories in the next decade will require tremendous increases in the accuracy of numerical waveforms modeling binary black holes, c…
View article: Einstein-Klein-Gordon system via Cauchy-characteristic evolution: Computation of memory and ringdown tail
Einstein-Klein-Gordon system via Cauchy-characteristic evolution: Computation of memory and ringdown tail Open
Cauchy-characteristic evolution (CCE) is a powerful method for accurately extracting gravitational waves at future null infinity. In this work, we extend the previously implemented CCE system within the numerical relativity code SpECTRE by…
View article: High-Precision Ringdown Surrogate Model for Non-Precessing Binary Black Holes
High-Precision Ringdown Surrogate Model for Non-Precessing Binary Black Holes Open
Highly precise and robust waveform models are required as improvements in detector sensitivity enable us to test general relativity with more precision than ever before. In this work, we introduce a spin-aligned surrogate ringdown model. T…
Scalarization of isolated black holes in scalar Gauss-Bonnet theory in the fixing-the-equations approach Open
One of the most promising avenues to perform numerical evolutions in theories beyond general relativity is the approach, a proposal in which new “driver” equations are added to the evolution equations in a way that allows for stable numeri…
View article: Binary neutron star mergers using a discontinuous Galerkin-finite difference hybrid method
Binary neutron star mergers using a discontinuous Galerkin-finite difference hybrid method Open
We present a discontinuous Galerkin-finite difference hybrid scheme that allows high-order shock capturing with the discontinuous Galerkin method for general relativistic magnetohydrodynamics in dynamical spacetimes. We present several opt…
View article: Toward a self-consistent framework for measuring black hole ringdowns
Toward a self-consistent framework for measuring black hole ringdowns Open
The ringdown portion of a binary black hole merger consists of a sum of modes, each containing an infinite number of tones that are exponentially damped sinusoids. In principle, these can be measured as gravitational-waves with observatori…
General relativistic force-free electrodynamics with a discontinuous Galerkin-finite difference hybrid method Open
Relativistic plasmas around compact objects can sometimes be approximated as being force-free. In this limit, the plasma inertia is negligible and the overall dynamics is governed by global electric currents. We present a novel numerical a…
View article: A Review of Gravitational Memory and BMS Frame Fixing in Numerical Relativity
A Review of Gravitational Memory and BMS Frame Fixing in Numerical Relativity Open
Gravitational memory effects and the BMS freedoms exhibited at future null infinity have recently been resolved and utilized in numerical relativity simulations. With this, gravitational wave models and our understanding of the fundamental…
View article: Improved frequency spectra of gravitational waves with memory in a binary-black-hole simulation
Improved frequency spectra of gravitational waves with memory in a binary-black-hole simulation Open
Numerical relativists can now produce gravitational waveforms with memory effects routinely and accurately. The gravitational-wave memory effect contains very low-frequency components, including a persistent offset. The presence of these c…
View article: Nonlinear Effects In Black Hole Ringdown From Scattering Experiments I: spin and initial data dependence of quadratic mode coupling
Nonlinear Effects In Black Hole Ringdown From Scattering Experiments I: spin and initial data dependence of quadratic mode coupling Open
We investigate quadratic quasinormal mode coupling in black hole spacetime through numerical simulations of single perturbed black holes using both numerical relativity and second-order black hole perturbation theory. Focusing on the domin…
View article: Black Hole Spectroscopy for Precessing Binary Black Hole Coalescences
Black Hole Spectroscopy for Precessing Binary Black Hole Coalescences Open
The spectroscopic study of black hole quasinormal modes in gravitational-wave ringdown observations is hindered by our ignorance of which modes should dominate astrophysical signals for different binary configurations, limiting tests of ge…
A positivity-preserving adaptive-order finite-difference scheme for GRMHD Open
We present an adaptive-order positivity-preserving conservative finite-difference scheme that allows a high-order solution away from shocks and discontinuities while guaranteeing positivity and robustness at discontinuities. This is achiev…
View article: Fully relativistic three-dimensional Cauchy-characteristic matching for physical degrees of freedom
Fully relativistic three-dimensional Cauchy-characteristic matching for physical degrees of freedom Open
A fully relativistic three-dimensional Cauchy-characteristic matching (CCM) algorithm is implemented for physical degrees of freedom in a numerical relativity code SpECTRE. The method is free of approximations and can be applied to any phy…