The SpECTRE Cauchy-characteristic evolution system for rapid, precise waveform extraction

Moxon, Jordan; Scheel, Mark A.; Teukolsky, Saul A.; Deppe, Nils; Fischer, Nils; Hébert, François; Kidder, Lawrence E.; Throwe, William

doi:10.48550/arxiv.2110.08635

Cited by 12 publications

(25 citation statements)

References 53 publications

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“…Though these templates should in principle be more accurate, due to difficulties in choosing initial data the waveforms of the kind (i) exhibit spurious oscillations, and are hence unsuited for our purposes. The latest implementation of the SpECTRE CCE module [82] is able to extract waveforms either from finished simulations or from a Generalized Harmonic simulation simultaneously running in SpECTRE, but this kind of data is currently not readily available.…”

Section: Multipolar Hierarchy At Mergermentioning

confidence: 99%

Numerical-relativity validation of effective-one-body waveforms in the intermediate-mass-ratio regime

Nagar,

Healy,

Lousto

et al. 2022

Preprint

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Section: Multipolar Hierarchy At Mergermentioning

confidence: 99%

Numerical-relativity validation of effective-one-body waveforms in the intermediate-mass-ratio regime

Nagar,

Healy,

Lousto

et al. 2022

Preprint

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“…Each simulation contains roughly 19 orbits prior to merger and is evolved until the waves from ringdown leave the computational domain. Unlike the evolutions in the SXS catalog, the full set of Weyl scalars and the strain have been extracted from these runs and the waveforms have been computed using the extrapolation technique described in [55] and the Cauchy-characteristic extraction (CCE) procedure that is outlined in [56,57]. Extrapolation is performed with the python module scri [27,[58][59][60] and CCE is run with SpECTRE's CCE module [56,57,61].…”

Section: Numerical Waveformsmentioning

confidence: 99%

“…This is the strain that can be found in the public SXS catalog. The other and more faithful extraction method, which is known as CCE, computes the strain by using the world tube data provided by a Cauchy evolution as the inner boundary data for a nonlinear evolution of the Einstein field equations on null hypersurfaces extending all the way to I + [56,57]. CCE requires freely specifying the strain on the initial null hypersurface labeled u = 0.…”

Section: Numerical Waveformsmentioning

confidence: 99%

“…for s 1 + s 2 + s 3 = 0, and then computing the corresponding Wigner 3 − j symbols to see which modes are excited [69]. Last, for the (2, ±2) modes, this is because these two modes of the strain experience an unexpected initial offset due to transient effects arising in the CCE evolution [42,56,57]. Meanwhile, in the news domain, by closer inspection one finds that the modes most strongly influenced by mapping to the super rest frame are the (3, ±2), (4, ±2), and (2, ±1) modes.…”

Section: Consequences Of Working In the Super Rest Framementioning

confidence: 99%

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High Precision Ringdown Modeling: Multimode Fits and BMS Frames

Zertuche,

Mitman,

Khera

et al. 2021

Preprint

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Quasi-normal mode (QNM) modeling is an invaluable tool for studying strong gravity, characterizing remnant black holes, and testing general relativity. To date, most studies have focused on the dominant (2, 2) mode, and have fit to standard strain waveforms from numerical relativity. But, as gravitational wave observatories become more sensitive, they can resolve higher-order modes. Multimode fits will be critically important, and in turn require a more thorough treatment of the asymptotic frame at I + . The first main result of this work is a method for systematically fitting a QNM model containing many modes to a numerical waveform produced using Cauchy-characteristic extraction, which is known to exhibit memory effects. We choose the modes to model based on their power contribution to the residual between numerical and model waveforms. We show that the all-mode mismatch improves by a factor of ∼ 10 5 when using multimode fitting as opposed to only fitting (2, ±2, n) modes. Our second main result addresses a critical point that has been overlooked in the literature: the importance of matching the Bondi-van der Burg-Metzner-Sachs (BMS) frame of the simulated gravitational wave to that of the QNM model. We show that by mapping the numerical relativity waveforms to the super rest frame, there is an improvement of ∼ 10 5 in the all-mode strain mismatch in the presence of memory, compared to using the strain whose BMS frame is not fixed. We illustrate the effectiveness of these modeling enhancements by applying them to families of waveforms produced by numerical relativity, and comparing our results to previous studies.

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“…Since characteristic formulations are based on null hypersurfaces, future null infinity can be naturally included in the computational domain. This is the region where quantities such as the Bondi news function are unambiguously defined, and so methods like Cauchy characteristic extraction (CCE) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] and matching (CCM) [16,17] can eliminate systematic extrapolation errors (the main alternative strategy for this is to use compactified hyperboloidal slices [18][19][20][21][22][23][24][25]).…”

Section: Introductionmentioning

confidence: 99%

Gauge structure of the Einstein field equations in Bondi-like coordinates

Giannakopoulos,

Bishop,

Hilditch

et al. 2021

Preprint

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A classic strategy [55,56] for well-posedness analysis of the CIVP is to reduce to an initial value problem (IVP). Well-posedness in L 2 for the IVP is characterized by strong hyperbolicity [57,58]. The IVP of a WH PDE system is ill-posed in L 2 , but it may be wellposed in a different norm [59]. This well-posedness is however delicate and, unlike the well-posedness of a SH PDE, can be broken by source terms. Well-posedness is a necessary condition for a numerical approximation of a PDE problem to converge to the continuum solution with increasing resolution. Convergence here is to be understood in terms of a discretized version of the norm in which the continuum problem is well-posed. An error estimate obtained from the numerical solutions of an ill-posed PDE problem should, a priori, be treated with great care. Therefore, well-posedness of the Bondi-like CIVP and CIBVP in GR is a particularly pressing open question for studies that focus on accuracy.The result of [54] was that two commonly used Bondilike gauges give rise to second order PDE systems that are only WH outside of the spherical context. Toy models that mimic this structure were used to demonstrate the effect of weak hyperbolicity in numerical experiments. In this paper we examine the cause of this result and, following [60,61], identify this weak hyperbolicity as a pure gauge effect. We argue that the construction upon radial null geodesics renders the vacuum EFE only WH in all Bondi-like gauges. We explicitly show the effect of weak hyperbolicity in numerical experiments in full GR formulated in the Bondi-Sachs proper gauge. This result implies that the CIVP and CIBVP of GR in vacuum are ill-posed in the simplest norms one might like to employ when formulated in these gauges. This issue can potentially be sidestepped by working with alternative norms, or higher derivatives of the metric, which might be taken explicitly as evolved variables, or simply placed within the norm under consideration. The latter tack has been successfully followed in for example [62][63][64][65].In Sec. II we map the Bondi-like equations and variables to the ADM ones, so that we can straightforwardly apply the aforementioned tools. In Sec. III we summarize the relevant theory and the structure of the principal part resulting from gauge freedom. In Sec. IV we analyze the affine null gauge [16], showing it to be only WH, both in the characteristic and in the equivalent ADM setups. In Sec. V A this analysis is repeated for the Bondi-Sachs gauge proper [66,67] in the ADM setup. In Sec. V B the calculation is repeated for the double null gauge [68]. We argue that all Bondi-like gauges possess this pure gauge structure. In Sec. VI we examine the numerical consqeuences of WH by performing robust-stabilitylike [69][70][71] tests. The results are compared against those of an artificial SH system. The tests are performed using the publicly available PITTNull thorn of the Einstein Toolkit [72]. We conclude in Sec. VII. Geometric units are used throughout. Our scripts are available in...

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The SpECTRE Cauchy-characteristic evolution system for rapid, precise waveform extraction

Cited by 12 publications

References 53 publications

Numerical-relativity validation of effective-one-body waveforms in the intermediate-mass-ratio regime

Numerical-relativity validation of effective-one-body waveforms in the intermediate-mass-ratio regime

High Precision Ringdown Modeling: Multimode Fits and BMS Frames

Gauge structure of the Einstein field equations in Bondi-like coordinates

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