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A Buonanno - One of the best experts on this subject based on the ideXlab platform.
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aligned spin neutron star black hole waveform model based on the effective one Body Approach and numerical relativity simulations
Physical Review D, 2020Co-Authors: A Matas, A Buonanno, T Dietrich, Tanja Hinderer, M Purrer, Francois Foucart, Michael Boyle, Matthew D Duez, Lawrence E Kidder, Harald P PfeifferAbstract:After the discovery of gravitational waves from binary black holes (BBHs) and binary neutron stars (BNSs) with the LIGO and Virgo detectors, neutron-star black holes (NSBHs) are the natural next class of binary systems to be observed. In this work, we develop a waveform model for aligned-spin NSBHs combining a BBH baseline waveform (available in the effective-one-Body Approach) with a phenomenological description of tidal effects (extracted from numerical-relativity simulations) and correcting the amplitude during the late inspiral, merger and ringdown to account for the NS tidal disruption. In particular, we calibrate the amplitude corrections using NSBH waveforms obtained with the numerical-relativity spectral Einstein code (SpEC) and the SACRA code. The model was calibrated using simulations with NS masses in the range 1.2–1.4 M⊙, tidal deformabilities up to 4200 (for a 1.2 M⊙ NS), and dimensionless BH spin magnitude up to 0.9. Based on the simulations used and on checking that sensible waveforms are produced, we recommend our model to be employed with a NS mass in the range 1–3 M⊙, tidal deformability 0–5000, and (dimensionless) BH spin magnitude up to 0.9. We also validate our model against two new, highly accurate NSBH waveforms with BH spin 0.9 and mass ratios 3 and 4, characterized by tidal disruption, produced with SpEC, and find very good agreement. Furthermore, we compute the unfaithfulness between waveforms from NSBH, BBH, and BNS systems, finding that it will be challenging for the Advanced LIGO-Virgo detector network at design sensitivity to distinguish different source classes. We perform a Bayesian parameter-estimation analysis on a synthetic numerical-relativity signal in zero noise to study parameter biases. Finally, we reanalyze GW170817, with the hypothesis that it is a NSBH. We do not find evidence to distinguish the BNS and NSBH hypotheses; however, the posterior for the mass ratio is shifted to less equal masses under the NSBH hypothesis.
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effects of neutron star dynamic tides on gravitational waveforms within the effective one Body Approach
Physical Review Letters, 2016Co-Authors: Tanja Hinderer, A Buonanno, Francois Foucart, Matthew D Duez, Lawrence E Kidder, Harald P Pfeiffer, A Taracchini, Jan Steinhoff, Mark A Scheel, Bela SzilagyiAbstract:Extracting the unique information on ultradense nuclear matter from the gravitational waves emitted by merging neutron-star binaries requires robust theoretical models of the signal. We develop a novel effective-one-Body waveform model that includes, for the first time, dynamic (instead of only adiabatic) tides of the neutron star as well as the merger signal for neutron-star–black-hole binaries. We demonstrate the importance of the dynamic tides by comparing our model against new numerical-relativity simulations of nonspinning neutron-star–black-hole binaries spanning more than 24 gravitational-wave cycles, and to other existing numerical simulations for double neutron-star systems. Furthermore, we derive an effective description that makes explicit the dependence of matter effects on two key parameters: tidal deformability and fundamental oscillation frequency.
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modeling extreme mass ratio inspirals within the effective one Body Approach
Physical Review Letters, 2010Co-Authors: Nicolás Yunes, A Buonanno, Scott A. Hughes, Coleman M MillerAbstract:: We present the first models of extreme-mass-ratio inspirals within the effective-one-Body (EOB) formalism, focusing on quasicircular orbits into nonrotating black holes. We show that the phase difference and (Newtonian-normalized) amplitude difference between analytical EOB and numerical Teukolsky-based gravitational waveforms can be reduced to less than or approximately 10{-1} rad and less than or approximately 2x10{-3}, respectively, after a 2-year evolution. The inclusion of post-Newtonian self-force terms in the EOB Approach leads to a phase disagreement of approximately 6-27 rad after a 2-year evolution. Such inclusion could also allow for the EOB modeling of waveforms from intermediate-mass-ratio, quasicircular inspirals.
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modeling extreme mass ratio inspirals within the effective one Body Approach
Physical Review Letters, 2010Co-Authors: Nicolás Yunes, A Buonanno, Scott A. Hughes, Coleman M Miller, Yi PanAbstract:We present the first models of extreme-mass-ratio inspirals within the effective-one-Body (EOB) formalism, focusing on quasicircular orbits into nonrotating black holes. We show that the phase difference and (Newtonian-normalized) amplitude difference between analytical EOB and numerical Teukolsky-based gravitational waveforms can be reduced to $\ensuremath{\lesssim}{10}^{\ensuremath{-}1}\text{ }\text{ }\mathrm{rad}$ and $\ensuremath{\lesssim}2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, respectively, after a 2-year evolution. The inclusion of post-Newtonian self-force terms in the EOB Approach leads to a phase disagreement of $\ensuremath{\sim}6--27\text{ }\text{ }\mathrm{rad}$ after a 2-year evolution. Such inclusion could also allow for the EOB modeling of waveforms from intermediate-mass-ratio, quasicircular inspirals.
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modeling extreme mass ratio inspirals within the effective one Body Approach
APS, 2010Co-Authors: Nicolás Yunes, A Buonanno, Scott A. Hughes, Coleman M MillerAbstract:We present the first models of extreme-mass-ratio inspirals within the effective-one-Body (EOB) formalism, focusing on quasicircular orbits into nonrotating black holes. We show that the phase difference and (Newtonian-normalized) amplitude difference between analytical EOB and numerical Teukolsky-based gravitational waveforms can be reduced to &10 � 1 rad and &2 � 10 � 3 , respectively, after a 2-year evolution. The inclusion of post-Newtonian self-force terms in the EOB Approach leads to a phase disagreement of � 6–27 rad after a 2-year evolution. Such inclusion could also allow for the EOB modeling of waveforms from intermediate-mass-ratio, quasicircular inspirals.
Thibault Damour - One of the best experts on this subject based on the ideXlab platform.
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the effective one Body Approach to the general relativistic two Body problem
Lecture Notes in Physics, 2016Co-Authors: Thibault Damour, Alessandro NagarAbstract:The two-Body problem in General Relativity has been the subject of many analytical investigations. After reviewing some of the methods used to tackle this problem (and, more generally, the N-Body problem), we focus on a new, recently introduced Approach to the motion and radiation of (comparable mass) binary systems: the Effective One Body (EOB) formalism. We review the basic elements of this formalism, and discuss some of its recent developments. Several recent comparisons between EOB predictions and Numerical Relativity (NR) simulations have shown the aptitude of the EOB formalism to provide accurate descriptions of the dynamics and radiation of various binary systems (comprising black holes or neutron stars) in regimes that are inaccessible to other analytical Approaches (such as the last orbits and the merger of comparable mass black holes). In synergy with NR simulations, post-Newtonian (PN) theory and Gravitational Self-Force (GSF) computations, the EOB formalism is likely to provide an efficient way of computing the very many accurate template waveforms that are needed for Gravitational Wave (GW) data analysis purposes.
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Effective one Body Approach to the dynamics of two spinning black holes with next-to-leading order spin-orbit coupling
Physical Review D - Particles, Fields, Gravitation and Cosmology, 2008Co-Authors: Thibault Damour, Piotr Jaranowski, Gerhard SchäferAbstract:Using a recent, novel Hamiltonian formulation of the gravitational interaction of spinning binaries, we extend the Effective One Body (EOB) description of the dynamics of two spinning black holes to next-to-leading order (NLO) in the spin-orbit interaction. The spin-dependent EOB Hamiltonian is constructed from four main ingredients: (i) a transformation between the ``effective'' Hamiltonian and the ``real'' one, (ii) a generalized effective Hamilton-Jacobi equation involving higher powers of the momenta, (iii) a Kerr-type effective metric (with Pad\'e-resummed coefficients) which depends on the choice of some basic ``effective spin vector'' $\bf{S}_{\rm eff}$, and which is deformed by comparable-mass effects, and (iv) an additional effective spin-orbit interaction term involving another spin vector $\bsigma$. As a first application of the new, NLO spin-dependent EOB Hamiltonian, we compute the binding energy of circular orbits (for parallel spins) as a function of the orbital frequency, and of the spin parameters. We also study the characteristics of the last stable circular orbit: binding energy, orbital frequency, and the corresponding dimensionless spin parameter $\hat{a}_{\rm LSO}\equiv c J_{\rm LSO}/\boldsymbol(G(H_{\rm LSO}/c^2)^2\boldsymbol)$. We find that the inclusion of NLO spin-orbit terms has a significant ``moderating'' effect on the dynamical characteristics of the circular orbits for large and parallel spins.
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coalescence of two spinning black holes an effective one Body Approach
Physical Review D, 2001Co-Authors: Thibault DamourAbstract:We generalize to the case of spinning black holes a recently introduced ``effective one-Body'' Approach to the general relativistic dynamics of binary systems. We show how to approximately map the conservative part of the third post-Newtonian (3PN) dynamics of two spinning black holes of masses ${m}_{1},$ ${m}_{2}$ and spins ${\mathit{S}}_{1},$ ${\mathit{S}}_{2}$ onto the dynamics of a non-spinning particle of mass $\ensuremath{\mu}\ensuremath{\equiv}{m}_{1}{m}_{2}{/(m}_{1}{+m}_{2})$ in a certain effective metric ${g}_{\ensuremath{\mu}\ensuremath{\nu}}^{\mathrm{eff}}{(x}^{\ensuremath{\lambda}};M,\ensuremath{\nu},\mathit{a})$ which can be viewed either as a spin deformation [with the deformation parameter $\mathit{a}\ensuremath{\equiv}{\mathit{S}}_{\mathrm{eff}}/M]$ of the recently constructed 3PN effective metric ${g}_{\ensuremath{\mu}\ensuremath{\nu}}^{\mathrm{eff}}{(x}^{\ensuremath{\lambda}};M,\ensuremath{\nu}),$ or as a $\ensuremath{\nu}$ deformation [with the comparable-mass deformation parameter $\ensuremath{\nu}\ensuremath{\equiv}{m}_{1}{m}_{2}{/(m}_{1}{+m}_{2}{)}^{2}]$ of a Kerr metric of mass $M\ensuremath{\equiv}{m}_{1}{+m}_{2}$ and (effective) spin ${\mathit{S}}_{\mathrm{eff}}\ensuremath{\equiv}[{1+3m}_{2}{/(4m}_{1})]{\mathit{S}}_{1}+[{1+3m}_{1}{/(4m}_{2})]{\mathit{S}}_{2}.$ The combination of the effective one-Body Approach, and of a Pad\'e definition of the crucial effective radial functions, is shown to define a dynamics with much improved post-Newtonian convergence properties, even for black hole separations of the order of $6 {GM/c}^{2}.$ The complete (conservative) phase-space evolution equations of binary spinning black hole systems are written down and their exact and approximate first integrals are discussed. This leads to the approximate existence of a two-parameter family of ``spherical orbits'' (with constant radius), and of a corresponding one-parameter family of ``last stable spherical orbits'' (LSSO). These orbits are of special interest for forthcoming LIGO-VIRGO-GEO gravitational wave observations. The binding energy and total angular momentum of LSSO's are studied in some detail. It is argued that for most (but not all) of the parameter space of two spinning holes the approximate (leading-order) effective one-Body Approach introduced here gives a reliable analytical tool for describing the dynamics of the last orbits before coalescence. This tool predicts, in a quantitative way, how certain spin orientations increase the binding energy of the LSSO. This leads to a detection bias, in LIGO-VIRGO-GEO observations, favoring spinning black hole systems, and makes it urgent to complete the conservative effective one-Body dynamics given here by adding (resummed) radiation reaction effects, and by constructing gravitational waveform templates that include spin effects. Finally, our Approach predicts that the spin of the final hole formed by the coalescence of two arbitrarily spinning holes never Approaches extremality.
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effective one Body Approach to general relativistic two Body dynamics
Physical Review D, 1999Co-Authors: A Buonanno, Thibault DamourAbstract:We map the general relativistic two-Body problem onto that of a test particle moving in an effective external metric. This effective-one-Body Approach defines, in a non-perturbative manner, the late dynamical evolution of a coalescing binary system of compact objects. The transition from the adiabatic inspiral, driven by gravitational radiation damping, to an unstable plunge, induced by strong spacetime curvature, is predicted to occur for orbits more tightly bound than the innermost stable circular orbit in a Schwarzschild metric of mass M 5m11m2 . The binding energy, angular momentum and orbital frequency of the innermost stable circular orbit for the time-symmetric two-Body problem are determined as a function of the mass ratio. @S0556-2821~99!04806-7#
Tim Baldsiefen - One of the best experts on this subject based on the ideXlab platform.
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reduced density matrix functional theory at finite temperature theoretical foundations
Physical Review A, 2015Co-Authors: Tim Baldsiefen, Attila Cangi, E. K. U. GrossAbstract:We present an ab initio Approach for grand-canonical ensembles in thermal equilibrium (eq) with local or nonlocal external potentials based on the one-reduced density matrix (1RDM). We show that equilibrium properties of a grand-canonical ensemble are determined uniquely by the eq-1RDM and establish a variational principle for the grand potential with respect to its 1RDM. We further prove the existence of a Kohn-Sham system capable of reproducing the 1RDM of an interacting system at finite temperature. Utilizing this Kohn-Sham system as an unperturbed system, we deduce a many-Body Approach to iteratively construct approximations to the correlation contribution of the grand potential.
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Reduced Density Matrix Functional Theory at Finite Temperature: Theoretical Foundations
arXiv: Other Condensed Matter, 2012Co-Authors: Tim Baldsiefen, Attila Cangi, E. K. U. GrossAbstract:We present an ab-initio Approach for grand canonical ensembles in thermal equilibrium with local or nonlocal external potentials based on the one-reduced density matrix. We show that equilibrium properties of a grand canonical ensemble are determined uniquely by the eq-1RDM and establish a variational principle for the grand potential with respect to its one-reduced density matrix. We further prove the existence of a Kohn-Sham system capable of reproducing the one-reduced density matrix of an interacting system at finite temperature. Utilizing this Kohn-Sham system as an unperturbed system, we deduce a many-Body Approach to iteratively construct approximations to the correlation contribution of the grand potential.
E. K. U. Gross - One of the best experts on this subject based on the ideXlab platform.
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reduced density matrix functional theory at finite temperature theoretical foundations
Physical Review A, 2015Co-Authors: Tim Baldsiefen, Attila Cangi, E. K. U. GrossAbstract:We present an ab initio Approach for grand-canonical ensembles in thermal equilibrium (eq) with local or nonlocal external potentials based on the one-reduced density matrix (1RDM). We show that equilibrium properties of a grand-canonical ensemble are determined uniquely by the eq-1RDM and establish a variational principle for the grand potential with respect to its 1RDM. We further prove the existence of a Kohn-Sham system capable of reproducing the 1RDM of an interacting system at finite temperature. Utilizing this Kohn-Sham system as an unperturbed system, we deduce a many-Body Approach to iteratively construct approximations to the correlation contribution of the grand potential.
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Reduced Density Matrix Functional Theory at Finite Temperature: Theoretical Foundations
arXiv: Other Condensed Matter, 2012Co-Authors: Tim Baldsiefen, Attila Cangi, E. K. U. GrossAbstract:We present an ab-initio Approach for grand canonical ensembles in thermal equilibrium with local or nonlocal external potentials based on the one-reduced density matrix. We show that equilibrium properties of a grand canonical ensemble are determined uniquely by the eq-1RDM and establish a variational principle for the grand potential with respect to its one-reduced density matrix. We further prove the existence of a Kohn-Sham system capable of reproducing the one-reduced density matrix of an interacting system at finite temperature. Utilizing this Kohn-Sham system as an unperturbed system, we deduce a many-Body Approach to iteratively construct approximations to the correlation contribution of the grand potential.
Oldrich Hungr - One of the best experts on this subject based on the ideXlab platform.
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Quantifying the relevance of rebound modelling Approaches using field experimental results
2014Co-Authors: Franck Bourrier, Oldrich Hungr, Luuk DorrenAbstract:The relevance of two rebound modeling Approaches classically used in rockfall simulation codes was assessed using field experiments of single rebounds. A lumped mass model, modeling the rock as a single material point, and a rigid Body one, explicitly accounting for the rock shape, were used. Both of them are efficient with only a few calibration parameters. The main limitations of each Approach are the calibration of a parameter accounting for both the roughness of the soil and the rock shape, for the lumped mass Approach, and the estimation of the rock length and height, for the rigid Body Approach. Finally, both rebound models require being improved to better predict the rotational velocities distribution.
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rockfall rebound comparison of detailed field experiments and alternative modelling Approaches
Earth Surface Processes and Landforms, 2012Co-Authors: Franck Bourrier, Frederic Berger, Pascal Tardif, Luuk Dorren, Oldrich HungrAbstract:The accuracy of rockfall trajectory simulations mainly rests on the calculation of the rebound of fragments following their impact on the slope. This paper is dedicated to the comparative analysis of two rebound modelling Approaches currently used in rockfall simulation using field experiments of single rebounds. The two Approaches consist in either modelling the rock as a single material point (lumped mass Approach) or in explicitly accounting for the fragment shape (rigid Body Approach). A lumped mass model accounting for the coupling between translational and rotational velocities and introducing a slope perturbation angle was used. A rigid Body Approach modelling the rocks as rigid locally deformable (in the vicinity of the contact surface) assemblies of spheres was chosen. The comparative analysis of the rebound models shows that both of them are efficient with only a few parameters. The main limitation of each Approach are the calibration of the value of the slope perturbation (‘roughness’) angle, for the lumped mass Approach, and the estimation of the rock length and height from field geological and historical analyses, for the rigid Body Approach. Finally, both rebound models require being improved in a pragmatic manner to better predict the rotational velocities distribution. Copyright © 2012 John Wiley & Sons, Ltd.
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Rockfall rebound: comparison of detailed field experiments and alternative modelling Approaches
Earth Surface Processes and Landforms, 2012Co-Authors: Franck Bourrier, Frederic Berger, Luuk Dorren, Philippe Tardif, Oldrich HungrAbstract:The accuracy of rockfall trajectory simulations mainly rests on the calculation of rocks rebound on the slope. This paper is dedicated to the comparative analysis of two rebound modelling Approaches currently used in rockfall simulation using field experiments of single rebounds. The two Approaches consist in either modelling the rock as a single material point (lumped mass Approach) or in explicitly accounting for the fragment shape (rigid Body Approach). The comparative analysis of the rebound models shows that both of them are efficient with only a few parameters. The main limitation of each Approach are the calibration of the value of the slope perturbation (roughness) angle, for the lumped mass Approach, and the estimation of the rock length and height from field geological and historical analyses, for the rigid Body Approach. Finally, both rebound models require being improved in a pragmatic manner to better predict the rotational velocities distribution.