A5077620063- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Black Holes and Theoretical Physics
- Geophysics and Sensor Technology
- Cosmology and Gravitation Theories
- Experimental and Theoretical Physics Studies
- Noncommutative and Quantum Gravity Theories
- Particle Accelerators and Free-Electron Lasers
- Astrophysics and Cosmic Phenomena
- Advanced Data Storage Technologies
- Superconducting Materials and Applications
- Seismic Imaging and Inversion Techniques
- Astro and Planetary Science
- Dynamics and Control of Mechanical Systems
- Relativity and Gravitational Theory
- Numerical methods for differential equations
- Geophysics and Gravity Measurements
- Parallel Computing and Optimization Techniques
- Structural Health Monitoring Techniques
- Tropical and Extratropical Cyclones Research
- Quantum Mechanics and Non-Hermitian Physics
- Ultrasonics and Acoustic Wave Propagation
- Fluid Dynamics Simulations and Interactions
- Model Reduction and Neural Networks
Louisiana State University
2012-2025
Max Planck Institute for Gravitational Physics
2002-2003
The University of Texas at Austin
2000
Numerical relativity has faced the problem that standard 3+1 simulations of black hole spacetimes without singularity excision and with avoiding lapse vanishing shift fail early on due to so-called slice stretching. We discuss conditions for nonexcision case effectively cure stretching allow run times $1000M$ more.
Gravitational waveforms from the inspiral and ring-down stages of binary black-hole coalescences can be modeled accurately by approximation/perturbation techniques in general relativity. Recent progress numerical relativity has enabled us to model also nonperturbative merger phase coalescence problem. This enables coherently search for all three nonspinning black holes using a single template bank. Taking our motivation these results, we propose family which inspiral, merger, that follow...
Recent progress in numerical relativity has enabled us to model the non-perturbative merger phase of binary black-hole coalescence problem. Based on these results, we propose a phenomenological family waveforms which can inspiral, and ring-down stages coalescence. We also construct template bank using this discuss its implementation search for signatures gravitational waves produced by coalescences data ground-based interferometers. This might enable extend present inspiral searches...
The final evolution of a binary-black-hole system gives rise to recoil velocity if an asymmetry is present in the emitted gravitational radiation. Measurements this effect for nonspinning binaries with unequal masses have pointed out that kick velocities $\ensuremath{\sim}175\text{ }\text{ }\mathrm{km}/\mathrm{s}$ can be reached mass ratio $\ensuremath{\simeq}0.36$. However, larger obtained equal-mass provided by spins. Using two independent methods we show merger such yields as large...
We provide a detailed analysis of several aspects the turduckening technique for evolving black holes. At analytical level we study constraint propagation general family BSSN-type formulation Einstein's field equations and identify under what conditions turducken procedure is rigorously justified violations will propagate to outside present high-resolution spherically symmetric studies which verify our predictions. Then three dimensional simulations single distorted holes using different...
Binary black-hole systems with spins aligned the orbital angular momentum are of special interest, as studies indicate that this configuration is preferred in nature due to non-vacuum environmental interactions, well post-Newtonian (PN) spin-orbit couplings. If two bodies differ, there can be a prominent beaming gravitational radiation during late plunge, causing recoil final merged black hole. In paper we perform an accurate and systematic study velocities from sequence equal-mass holes...
We present results from a new code for binary black hole evolutions using the moving-puncture approach, implementing finite differences in generalized coordinates, and allowing spacetime to be covered with multiple communicating nonsingular coordinate patches. Here we consider regular Cartesian near-zone, adapted spherical grids covering wave zone. The efficiencies resulting use of coordinates allow us maintain sufficient grid resolution an artificial outer boundary location which is...
The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational-wave data analysis communities. purpose NINJA to study sensitivity existing search algorithms using numerically generated waveforms foster closer collaboration We describe results first which focused on gravitational from binary black hole coalescence. Ten groups contributed were used generate set signals. These signals injected into simulated set, designed...
We perform 3+1 general relativistic simulations of rotating core collapse in the context collapsar model for long gamma-ray bursts. employ a realistic progenitor, rotation based on results stellar evolution calculations, and simplified equation state. Our track self-consistently collapse, bounce, postbounce phase, black hole formation, subsequent early hyperaccretion phase. extract gravitational waves from spacetime curvature identify unique wave signature associated with phase formation.
A key result of isotropic loop quantum cosmology is the existence a bounce which occurs when energy density matter field approaches universal maximum close to Planck density. Though has been exhibited in various models, due severe computational challenges, some important questions have so far remained unaddressed. These include demonstration for widely spread states, its detailed properties states probes regions volume and reliability continuum effective spacetime description general. In...
Determining the final spin of a black hole (BH) binary is question key importance in astrophysics. Modeling this quantity general made difficult by fact that it depends on seven-dimensional space parameters characterizing two initial holes. However, special cases, when symmetries can be exploited, description become simpler. For BH binaries with unequal masses but equal spins which are aligned orbital angular momentum, we show use recent simulations and basic exact constraints derived from...
In recent years, numerical simulations with Gaussian initial states have demonstrated the existence of a quantum bounce in loop cosmology various models.A key issue pertaining to robustness and associated physics is understand evolution for more general which may depart significantly from Gaussianity no well defined peakedness properties.The analysis such states, including squeezed highly non-Gaussian has been computationally challenging until now.In this manuscript, we overcome these...
ABSTRACT Neutron star (NS) mergers where both stars have negligible spins are commonly considered as the most likely ‘standard’ case. In globular clusters, however, majority of NSs been spun up to millisecond (ms) periods and, based on observed systems, we estimate that a non-negligible fraction all double NS ($\sim 4\pm 2\, {{\ \rm per\ cent}}$) contains one component with spin (few) ms. We use Lagrangian numerical relativity code SPHINCS_BSSN simulate has no and other dimensionless...
Binary black hole systems with spins aligned the orbital angular momentum are of special interest, as they may be preferred end state inspiral generic supermassive binary systems. In view this, we have computed and merger a large set equal-mass holes but otherwise arbitrary. By least-square fitting results these simulations, constructed two "spin diagrams" which provide straightforward information about recoil velocity |vkick| final spin afin in terms dimensionless a1 a2 initial holes....
Due to the numerical complexities of studying evolution in an anisotropic quantum spacetime, comparison isotropic models, physics loop quantized models has remained largely unexplored. In particular, robustness bounce and validity effective dynamics have so far not been established. Our analysis fills these gaps for case vacuum Bianchi-I spacetime. To efficiently solve Hamiltonian constraint we perform implementation Cactus framework which is conventionally used applications relativity....
Abstract The ejection of neutron-rich matter is one the most important consequences a neutron star merger. While bulk ejected at fast, but non-relativistic velocities (∼0.2c), small amount mildly relativistic dynamic ejecta have been seen in number numerical simulations. Such can far reaching observational ranging from shock breakout burst gamma-rays promptly after merger, to an early (∼1 hour post-merger) blue kilonova precursor signal, synchrotron emission years merger (‘kilonova...
We describe a generic infrastructure for time evolution simulations in numerical relativity using multiple grid patches. After motivation of this approach, we discuss the relative advantages global and patch-local tensor bases. both our multi-patch scheme, comment on adaptive integrators parallelization. also various patch system topologies that provide spherical outer and/or inner boundaries. employ penalty inter-patch boundary conditions, demonstrate stability accuracy three-dimensional...
to turducken (turduckens, turduckening, turduckened, turduckened) [math.]: To stuff a black hole. We analyze and apply an alternative hole excision based on smoothing the interior of holes with arbitrary initial data, solving vacuum Einstein evolution equations everywhere. By deriving constraint propagation system for our hyperbolic formulation BSSN we rigorously prove that constraints propagate causally so any violations introduced inside cannot affect exterior spacetime. present evolutions...
We present a detailed analysis of binary black hole evolutions in the last orbit and demonstrate consistent convergent results for trajectories individual bodies. The gauge choice can significantly affect overall accuracy evolution. It is possible to reconcile certain gauge-dependent discrepancies by examining convergence limit. illustrate these using an initial data set recently evolved Brügmann et al. [Phys. Rev. Lett. 92, 211101 (2004)10.1103/PhysRevLett.92.211101]. For our highest...
We present numerical results from three-dimensional evolutions of scalar perturbations Kerr black holes. Our simulations make use a high-order accurate multiblock code which naturally allows for adapted grids and smooth inner (excision) outer boundaries. focus on the quasinormal ringing phase, presenting systematic method extraction mode frequencies amplitudes comparing our against perturbation theory. The detection single in ringdown waveform measurement mass spin hole; multimode would...
The motion of a charged particle is influenced by the self-force arising from particle's interaction with its own field. In curved spacetime, this depends on entire past history and difficult to evaluate. As result, all existing evaluations in spacetime are for particles moving along fixed trajectory. Here, first time, we overcome long-standing limitation present fully self-consistent orbits waveforms scalar around Schwarzschild black hole.