Numerical relativity in spherical coordinates: A new dynamical spacetime and general relativistic MHD evolution framework for the Einstein Toolkit

Mewes, Vassilios; Zlochower, Yosef; Campanelli, Manuela; Baumgarte, Thomas W.; Etienne, Z. B.; Armengol, Federico G. Lopez; Cipolletta, Federico

doi:10.1103/physrevd.101.104007

Cited by 27 publications

(34 citation statements)

References 196 publications

(315 reference statements)

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“…-The Einstein equations are then solved with free-evolution schemes like BSSNOK [238][239][240] or Z4c [241][242][243][244] based on the conformal decomposition of the metric fields. The latter scheme (and variation on the original proposal [245][246][247]) incorporates improved constraints propagation and damping properties with respect to BSSNOK and is thus preferable to BSSNOK in nonvacuum spacetimes. Neutron star spacetime evolutions are also performed with the generalized harmonic scheme [248,249].…”

Section: A Appendix A: Numerical-relativity Methodsmentioning

confidence: 99%

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Neutron star merger remnants

Bernuzzi

2020

Gen Relativ Gravit

122

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Binary neutron star mergers observations are a unique way to constrain fundamental physics and astrophysics at the extreme. The interpretation of gravitational-wave events and their electromagnetic counterparts crucially relies on general-relativistic models of the merger remnants. Quantitative models can be obtained only by means of numerical relativity simulations in $$3+1$$ 3 + 1 dimensions including detailed input physics for the nuclear matter, electromagnetic and weak interactions. This review summarizes the current understanding of merger remnants focusing on some of the aspects that are relevant for multimessenger observations.

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Section: A Appendix A: Numerical-relativity Methodsmentioning

confidence: 99%

“…An outer spherical grid composed of multi-patches is sometimes used to extend the radiation zone [298,299]. Spherical grids are being explored and could help for long-term simulations of the postmerger phase [247].…”

Section: A Appendix A: Numerical-relativity Methodsmentioning

confidence: 99%

Neutron star merger remnants

Bernuzzi

2020

Gen Relativ Gravit

122

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“…We then use suitable finite volume discretizations (in Cartesian and spherical coordinates, Cerdá-Durán et al 2008) for the integration of intercell fluxes in our time-marching scheme. Alternative approaches have been employed, for example, by Montero et al (2014) and Mewes et al (2020), wherein all information about the underlying coordinate system is encoded in geometrical source terms.…”

Section: Introductionmentioning

confidence: 99%

Computational general relativistic force-free electrodynamics

Mahlmann

Aloy

Mewes

et al. 2021

A&A

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General relativistic force-free electrodynamics is one possible plasma-limit employed to analyze energetic outflows in which strong magnetic fields are dominant over all inertial phenomena. The amazing images of black hole (BH) shadows from the Galactic Center and the M87 galaxy provide a first direct glimpse into the physics of accretion flows in the most extreme environments of the universe. The efficient extraction of energy in the form of collimated outflows or jets from a rotating BH is directly linked to the topology of the surrounding magnetic field. We aim at providing a tool to numerically model the dynamics of such fields in magnetospheres around compact objects, such as BHs and neutron stars. To do so, we probe their role in the formation of high energy phenomena such as magnetar flares and the highly variable teraelectronvolt emission of some active galactic nuclei. In this work, we present numerical strategies capable of modeling fully dynamical force-free magnetospheres of compact astrophysical objects. We provide implementation details and extensive testing of our implementation of general relativistic force-free electrodynamics in Cartesian and spherical coordinates using the infrastructure of the EINSTEIN TOOLKIT. The employed hyperbolic/parabolic cleaning of numerical errors with full general relativistic compatibility allows for fast advection of numerical errors in dynamical spacetimes. Such fast advection of divergence errors significantly improves the stability of the general relativistic force-free electrodynamics modeling of BH magnetospheres.

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“…In particular, we follow Refs. [78] (see Table 1 of that reference) and change the sign of g tθ , g rθ , g φθ and their symmetric permutations. The metric component g φφ tends to zero towards the axis, so we enforce g φφ = 1 × 10 −14 if this component takes a smaller value at the θ-face and corners of the physical cells next to the axis.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…[44] for further comments on current computational limitations, and see Ref. [78] for NR simulations in spherical coordinates.…”

Section: Introductionmentioning

confidence: 99%

Handing off the outcome of binary neutron star mergers for accurate and long-term post-merger simulations

Armengol¹,

Etienne²,

Noble³

et al. 2021

Preprint

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We perform binary neutron star (BNS) merger simulations in full dynamical general relativity with IllinoisGRMHD, on a Cartesian grid with adaptive-mesh refinement. After the remnant black hole (BH) has become nearly stationary, the evolution of the surrounding accretion disk on Cartesian grids over long timescales (∼1s) is suboptimal, as the plasma flows obliquely across coordinate lines and numerical errors quickly dissipate angular momentum from the disk. To address this, we present the HandOff, a set of computational tools that enables the transfer of general relativistic magnetohydrodynamic (GRMHD) and spacetime data from IllinoisGRMHD to Harm3d, a GRMHD code that specializes in modeling BH accretion disks in static spacetimes over long timescales, making use of general coordinate systems with spherical topology. We demonstrate that the HandOff allows for a smooth and reliable transition of GRMHD fields and spacetime data, enabling us to efficiently and reliably evolve BNS dynamics well beyond merger. We also discuss future plans, which involve incorporating advanced equations of state and neutrino physics into BNS simulations using the HandOff approach.

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Numerical relativity in spherical coordinates: A new dynamical spacetime and general relativistic MHD evolution framework for the Einstein Toolkit

Cited by 27 publications

References 196 publications

Neutron star merger remnants

Neutron star merger remnants

Computational general relativistic force-free electrodynamics

Handing off the outcome of binary neutron star mergers for accurate and long-term post-merger simulations

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