The black hole accretion code

Porth, Oliver; Olivares, Héctor; Mizuno, Yosuke; Younsi, Ziri; Rezzolla, Luciano; Mościbrodzka, Monika; Falcke, H.; Krämer, M.

doi:10.1186/s40668-017-0020-2

Cited by 238 publications

(317 citation statements)

References 157 publications

(299 reference statements)

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“…All of these methods are implemented in the open source MPI-AMRVAC framework (Porth et al 2014;Xia et al 2018) and can be used to analyze particle dynamics in evolving electromagnetic fields from MHD simulations. The extension of the methods presented here to general relativistic covariant formulations is planned for future work in the general relativistic MHD code BHAC (Porth et al 2017). The implicit particle pusher that is briefly presented here will be extended to the fully implicit relativistic PIC code xPic (F. Bacchini et al 2018, in preparation).…”

Section: Discussionmentioning

confidence: 99%

A Comprehensive Comparison of Relativistic Particle Integrators

Ripperda

Bacchini

Teunissen

et al. 2018

ApJS

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We compare relativistic particle integrators commonly used in plasma physics, showing several test cases relevant for astrophysics. Three explicit particle pushers are considered, namely, the Boris, Vay, and HigueraCary schemes. We also present a new relativistic fully implicit particle integrator that is energy conserving. Furthermore, a method based on the relativistic guiding center approximation is included. The algorithms are described such that they can be readily implemented in magnetohydrodynamics codes or Particle-in-Cell codes. Our comparison focuses on the strengths and key features of the particle integrators. We test the conservation of invariants of motion and the accuracy of particle drift dynamics in highly relativistic, mildly relativistic, and non-relativistic settings. The methods are compared in idealized test cases, i.e., without considering feedback onto the electrodynamic fields, collisions, pair creation, or radiation. The test cases include uniform electric and magnetic fields, E B fields, force-free fields, and setups relevant for high-energy astrophysics, e.g., a magnetic mirror, a magnetic dipole, and a magnetic null. These tests have direct relevance for particle acceleration in shocks and in magnetic reconnection.

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Section: Discussionmentioning

confidence: 99%

A Comprehensive Comparison of Relativistic Particle Integrators

Ripperda

Bacchini

Teunissen

et al. 2018

ApJS

Self Cite

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“…In both cases the normalization is such that the density-weighted average of β −1 is 10 −2 , and we perturb the initial state via (5) with ∆ 0 = 0.02 and k R , k z = 2π/5. The single-loop variant is comparable to standard tori widely used in the literature, for example when testing and demonstrating a new GRMHD code (Gammie et al 2003;Antón et al 2006;White et al 2016;Porth et al 2017) or comparing such codes (Porth et al 2019), though around a nonspinning black hole here. It is similar to a scaleddown version of simulation B.…”

Section: B Comparison With Smaller Torimentioning

confidence: 99%

The Structure of Radiatively Inefficient Black Hole Accretion Flows

White

Quataert

Gammie

2020

ApJ

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We run three long-timescale general-relativistic magnetohydrodynamic simulations of radiatively inefficient accretion flows onto non-rotating black holes. Our aim is to achieve steady-state behavior out to large radii and understand the resulting flow structure. A simulation with adiabatic index Γ = 4/3 and small initial alternating poloidal magnetic field loops is run to a time of 440,000 GM/c 3 , reaching inflow equilibrium inside a radius of 370 GM/c 2 . Variations with larger alternating field loops and with Γ = 5/3 are run to 220,000 GM/c 3 , attaining equilibrium out to 170 GM/c 2 and 440 GM/c 2 . There is no universal self-similar behavior obtained at radii in inflow equilibrium: the Γ = 5/3 simulation shows a radial density profile with power law index ranging from −1 in the inner regions to −1/2 in the outer regions, while the others have a power-law slope ranging from −1/2 to close to −2. Both simulations with small field loops reach a state with polar inflow of matter, while the more ordered initial field has polar outflows. However, unbound outflows remove only a factor of order unity of the inflowing material over a factor of ∼ 300 in radius. Our results suggest that the dynamics of radiatively inefficient accretion flows are sensitive to how the flow is fed from larger radii, and may differ appreciably in different astrophysical systems. Millimeter images appropriate for Sgr A* are qualitatively (but not quantitatively) similar in all simulations, with a prominent asymmetric image due to Doppler boosting.

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“…Incorporating all these effects into analytic models is difficult, and thus general relativistic magnetohydrodynamic (GRMHD) simulations are the most promising avenues for theoretical modeling (Gammie et al 2003;Sadowski et al 2014;White et al 2016;Porth et al 2017). These simulations solve the equations of MHD in the Kerr metric for a rotating black hole in 3+1 dimensions, naturally capturing the magnetorotational instability (MRI), the formation of jets, turbulence, and general relativistic effects.…”

Section: Introductionmentioning

confidence: 99%

On the comparison of AGN with GRMHD simulations: I. Sgr A*

Anantua

Ressler

Quataert

2020

Monthly Notices of the Royal Astronomical Society

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We present models of Galactic Center emission in the vicinity of Sagittarius A* that use parametrizations of the electron temperature or energy density. These models include those inspired by two-temperature general relativistic magnetohydrodynamic (GRMHD) simulations as well as jet-motivated prescriptions generalizing equipartition of particle and magnetic energies. From these models, we calculate spectra and images and classify them according to their distinct observational features. Some models produce morphological and spectral features, e.g., image sizes, the sub-mm bump and low frequency spectral slope compatible with observations. Models with spectra consistent with observations produce the most compact images, with the most prominent, asymmetric photon rings. Limb brightened outflows are also visible in many models. Of all the models we consider, that which represents the current data the best is one in which electrons are relativistically hot when magnetic pressure is larger than the thermal pressure, but cold (i.e., negligibly contributing to the emission) otherwise. This work is part of a series also applying the "observing" simulations methodology to near-horizon regions of supermassive black holes in M87 and 3C 279.

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The black hole accretion code

Cited by 238 publications

References 157 publications

A Comprehensive Comparison of Relativistic Particle Integrators

A Comprehensive Comparison of Relativistic Particle Integrators

The Structure of Radiatively Inefficient Black Hole Accretion Flows

On the comparison of AGN with GRMHD simulations: I. Sgr A*

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