Lessons for adaptive mesh refinement in numerical relativity

Radia, Miren; Sperhake, Ulrich; Drew, Amelia; Clough, Katy; Figueras, Pau; Lim, Eugene A.; Ripley, Justin L.; Aurrekoetxea, Josu C.; França, Tiago; Helfer, Thomas

doi:10.48550/arxiv.2112.10567

Cited by 6 publications

(10 citation statements)

References 120 publications

(237 reference statements)

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“…With the upper range, we arrive at a conservative total error budget for discretisation and extraction of about 4 %. As a final test, we have repeated the mini and +mini collisions for d = 101 M with the independent GRChombo code [97,98] using the CCZ4 formulation [95] and obtain the same results within ≈1.5 %. Bearing in mind these tests and a 4 % error budget, we next study the dynamics of the BS head-on collisions with and without our adjustment of the initial data.…”

Section: Convergence and Numerical Uncertaintiesmentioning

confidence: 93%

Malaise and remedy of binary boson-star initial data

Helfer

Sperhake

Croft

et al. 2022

Class. Quantum Grav.

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Through numerical simulations of boson-star head-on collisions, we explore the quality of binary initial data obtained from the superposition of single-star spacetimes. Our results demonstrate that evolutions starting from a plain superposition of individual boosted boson-star spacetimes are vulnerable to significant unphysical artefacts. For equal-mass binaries, these difficulties can be overcome with a simple modification of the initial data suggested in Ref.[1] for collisions of oscillatons. While we specifically consider massive complex scalar field boson star models of very high and low compactness, we conjecture that this vulnerability be also present in other kinds of exotic compact systems and hence needs to be addressed.

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Section: Convergence and Numerical Uncertaintiesmentioning

confidence: 93%

Malaise and remedy of binary boson-star initial data

Helfer

Sperhake

Croft

et al. 2022

Class. Quantum Grav.

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“…We use an adapted version of the GRChombo numerical relativity framework [63][64][65] with the metric compo-nents and their derivatives calculated analytically at each point rather than stored on the grid. The evolution of the Proca field components follows the standard method of lines, with a fourth-order Runge-Kutta time integrator and fourth-order finite difference stencils.…”

Section: Numerical Details and Convergencementioning

confidence: 99%

The problem with Proca: ghost instabilities in self-interacting vector fields

Clough¹,

Helfer²,

Witek³

et al. 2022

Preprint

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Massive vector fields feature in several areas of particle physics, e.g., as carriers of weak interactions, dark matter candidates, or as an effective description of photons in a plasma. Here we investigate vector fields with self-interactions by replacing the mass term in the Proca equation with a general potential. We show that this seemingly benign modification inevitably introduces ghost instabilities of the same kind as those recently identified for vector-tensor theories of modified gravity (but in this simpler, minimally coupled theory). It has been suggested that nonperturbative dynamics may drive systems away from such instabilities. We demonstrate that this is not the case by evolving a self-interacting Proca field on a black hole background, where it grows due to the superradiant instability. The system initially evolves as in the massive case, but instabilities are triggered in a finite time once the self-interaction becomes significant. These instabilities have implications for the formation of condensates of massive, self-interacting vector bosons, the possibility of spin-one bosenovae, vector dark matter models, and effective models for interacting photons in a plasma.

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“…In this work, we use GRCHOMBO, a multipurpose numerical relativity code [126][127][128] which solves the BSSN [129,130] and CCZ4 [131,132] formulations of the Einstein equations. In addition, we use the standard moving puncture gauge conditions [133][134][135] for numerically stable evolutions of black hole spacetimes.…”

Section: Numerical Methodology Evolution Equationsmentioning

confidence: 99%

Where is the ringdown? Reconstructing quasinormal modes from dispersive waves

Aurrekoetxea¹,

Ferreira²,

Clough³

et al. 2022

Preprint

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We study the generation and propagation of gravitational waves in scalar-tensor gravity using numerical relativity simulations of scalar field collapses beyond spherical symmetry. This allows us to compare the tensor and additional massive scalar waves that are excited. As shown in previous work in spherical symmetry, massive propagating scalar waves decay faster than 1/r and disperse, resulting in an inverse chirp. These effects obscure the ringdown in any extracted signal by mixing it with the transient responses of the collapse during propagation. In this paper we present a simple method to rewind the extracted signals to horizon formation, which allows us to clearly identify the ringdown phase and extract the amplitudes of the scalar quasinormal modes, quantifying their excitation in strong gravity events and verifying the frequencies to perturbative calculations. The effects studied are relevant to any theories in which the propagating waves have a dispersion relation, including the tensor case.

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Lessons for adaptive mesh refinement in numerical relativity

Cited by 6 publications

References 120 publications

Malaise and remedy of binary boson-star initial data

Malaise and remedy of binary boson-star initial data

The problem with Proca: ghost instabilities in self-interacting vector fields

Where is the ringdown? Reconstructing quasinormal modes from dispersive waves

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