Primitive Variable Solvers for Conservative General Relativistic Magnetohydrodynamics

Noble, Scott C.; Gammie, Charles F.; McKinney, Jonathan C.; Zanna, L. Del

doi:10.1086/500349

Cited by 308 publications

(415 citation statements)

References 19 publications

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“…We developed H-AMR based on a 2D serial open-source code HARM2D (Gammie et al 2003;Noble et al 2006). H-AMR performs 10 times faster on a GPU than on a 16-core CPU.…”

Section: H-amr ("Hammer") Codementioning

confidence: 99%

Formation of precessing jets by tilted black hole discs in 3D general relativistic MHD simulations

Liska

Hesp

Tchekhovskoy

et al. 2017

Monthly Notices of the Royal Astronomical Society: Letters

329

334

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Gas falling into a black hole (BH) from large distances is unaware of BH spin direction, and misalignment between the accretion disc and BH spin is expected to be common. However, the physics of tilted discs (e.g., angular momentum transport and jet formation) is poorly understood. Using our new GPU-accelerated code H-AMR, we performed 3D general relativistic magnetohydrodynamic simulations of tilted thick accretion discs around rapidly spinning BHs, at the highest resolution to date. We explored the limit where disc thermal pressure dominates magnetic pressure, and showed for the first time that, for different magnetic field strengths on the BH, these flows launch magnetized relativistic jets propagating along the rotation axis of the tilted disc (rather than of the BH). If strong large-scale magnetic flux reaches the BH, it bends the inner few gravitational radii of the disc and jets into partial alignment with the BH spin. On longer time scales, the simulated disc-jet system as a whole undergoes LenseThirring precession and approaches alignment, demonstrating for the first time that jets can be used as probes of disc precession. When the disc turbulence is well-resolved, our isolated discs spread out, causing both the alignment and precession to slow down.

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“…We developed H-AMR based on a 2D serial open-source code HARM2D (Gammie et al 2003;Noble et al 2006). H-AMR performs 10 times faster on a GPU than on a 16-core CPU.…”

Section: H-amr ("Hammer") Codementioning

confidence: 99%

Formation of precessing jets by tilted black hole discs in 3D general relativistic MHD simulations

Liska

Hesp

Tchekhovskoy

et al. 2017

Monthly Notices of the Royal Astronomical Society: Letters

329

334

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“…We implemented the model described in §2 and §3 into the conservative GRMHD code, HARM2D (High-Accuracy Relativistic Magnetohydrodynamics; Gammie, McKinney & Tóth 2003;Noble et al 2006). To speed up the computations, we parallelised the code using OpenMP and MPI via domain decomposition.…”

Section: Tests Of Numerical Implementationmentioning

confidence: 99%

Electron thermodynamics in GRMHD simulations of low-luminosity black hole accretion

Ressler

Tchekhovskoy

Quataert

et al. 2015

Mon. Not. R. Astron. Soc.

174

238

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Simple assumptions made regarding electron thermodynamics often limit the extent to which general relativistic magnetohydrodynamic (GRMHD) simulations can be applied to observations of low-luminosity accreting black holes. We present, implement, and test a model that self-consistently evolves an entropy equation for the electrons and takes into account the effects of spatially varying electron heating and relativistic anisotropic thermal conduction along magnetic field lines. We neglect the back-reaction of electron pressure on the dynamics of the accretion flow. Our model is appropriate for systems accreting at ≪ 10 −5 of the Eddington accretion rate, so radiative cooling by electrons can be neglected. It can be extended to higher accretion rates in the future by including electron cooling and proton-electron Coulomb collisions. We present a suite of tests showing that our method recovers the correct solution for electron heating under a range of circumstances, including strong shocks and driven turbulence. Our initial applications to axisymmetric simulations of accreting black holes show that (1) physically-motivated electron heating rates that depend on the local magnetic field strength yield electron temperature distributions significantly different from the constant electron to proton temperature ratios assumed in previous work, with higher electron temperatures concentrated in the coronal region between the disc and the jet; (2) electron thermal conduction significantly modifies the electron temperature in the inner regions of black hole accretion flows if the effective electron mean free path is larger than the local scale-height of the disc (at least for the initial conditions and magnetic field configurations we study). The methods developed in this work are important for producing more realistic predictions for the emission from accreting black holes such as Sagittarius A* and M87; these applications will be explored in future work.

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“…This is not trivial because, although the relations U(P) are analytic, the inverse relations P(U) are not. In general, one can do the inversion by numerically solving a system of nonlinear algebric equations [56]. Here, we discuss the case where the EOS is given by Eq.…”

Section: Recovery Of Primitive Variablesmentioning

confidence: 99%

Relativistic magnetohydrodynamics in dynamical spacetimes: Numerical methods and tests

et al. 2005

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Many problems at the forefront of theoretical astrophysics require the treatment of magnetized fluids in dynamical, strongly curved spacetimes. Such problems include the origin of gamma-ray bursts, magnetic braking of differential rotation in nascent neutron stars arising from stellar core collapse or binary neutron star merger, the formation of jets and magnetized disks around newborn black holes, etc. To model these phenomena, all of which involve both general relativity (GR) and magnetohydrodynamics (MHD), we have developed a GRMHD code capable of evolving MHD fluids in dynamical spacetimes. Our code solves the Einstein-Maxwell-MHD system of coupled equations in axisymmetry and in full 3+1 dimensions. We evolve the metric by integrating the BSSN equations, and use a conservative, shock-capturing scheme to evolve the MHD equations. Our code gives accurate results in standard MHD code-test problems, including magnetized shocks and magnetized Bondi flow. To test our code's ability to evolve the MHD equations in a dynamical spacetime, we study the perturbations of a homogeneous, magnetized fluid excited by a gravitational plane wave, and we find good agreement between the analytic and numerical solutions.

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Primitive Variable Solvers for Conservative General Relativistic Magnetohydrodynamics

Cited by 308 publications

References 19 publications

Formation of precessing jets by tilted black hole discs in 3D general relativistic MHD simulations

Formation of precessing jets by tilted black hole discs in 3D general relativistic MHD simulations

Electron thermodynamics in GRMHD simulations of low-luminosity black hole accretion

Relativistic magnetohydrodynamics in dynamical spacetimes: Numerical methods and tests

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