Relativistic hydrodynamics in the presence of puncture black holes

Faber, Joshua A.; Baumgarte, Thomas W.; Etienne, Z. B.; Shapiro, Stuart L.; Taniguchi, Keisuke

doi:10.1103/physrevd.76.104021

Cited by 38 publications

(61 citation statements)

References 72 publications

(150 reference statements)

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“…The other will be to identify a gauge that can drive the metric inside the horizon to a puncture-like solution, a technique which has been used with great success in binary black hole simulations [62]. Simple experimentation with vacuum black holes and black holes immersed in hydrodynamic fluid suggest that there exist such gauge choices [63].…”

Section: Discussionmentioning

confidence: 99%

Magnetorotational collapse of very massive stars to black holes in full general relativity

2007

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We perform axisymmetric simulations of the magnetorotational collapse of very massive stars in full general relativity. Our simulations are applicable to the collapse of supermassive stars with masses M 10 3 M⊙ and to very massive Population III stars. We model our initial configurations by n = 3 polytropes, uniformly rotating near the mass-shedding limit and at the onset of radial instability to collapse. The ratio of magnetic to rotational kinetic energy in these configurations is chosen to be small (1% and 10%). We find that such magnetic fields do not affect the initial collapse significantly. The core collapses to a black hole, after which black hole excision is employed to continue the evolution long enough for the hole to reach a quasi-stationary state. We find that the black hole mass is M h = 0.95M and its spin parameter is J h /M 2 h = 0.7, with the remaining matter forming a torus around the black hole. The subsequent evolution of the torus depends on the strength of the magnetic field. We freeze the spacetime metric ("Cowling approximation") and continue to follow the evolution of the torus after the black hole has relaxed to quasi-stationary equilibrium. In the absence of magnetic fields, the torus settles down following ejection of a small amount of matter due to shock heating. When magnetic fields are present, the field lines gradually collimate along the hole's rotation axis. MHD shocks and the magnetorotational instability (MRI) generate MHD turbulence in the torus and stochastic accretion onto the central black hole. When the magnetic field is strong, a wind is generated in the torus, and the torus undergoes radial oscillations that drive episodic accretion onto the hole. These oscillations produce long-wavelength gravitational waves potentially detectable by the Laser Interferometer Space Antenna (LISA). The final state of the magnetorotational collapse always consists of a central black hole surrounded by a collimated magnetic field and a hot, thick accretion torus. This system is a viable candidate for the central engine of a long-soft gamma-ray burst.

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Section: Discussionmentioning

confidence: 99%

Magnetorotational collapse of very massive stars to black holes in full general relativity

2007

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“…We obtain good agreement between these two independent codes. Our code has also been used to study the collapse of very massive, magnetized, rotating stars to black hole [21], evolution of merging BHBH [53] and BHNS binaries [20], and the evolution of relativistic hydrodynamic matter in the presence of puncture black holes [54]. Recently, our code has been generalized to incorporate (optically thick) radiation transport and its feedback on hydrodynamic matter [55].…”

Section: Fluid µνmentioning

confidence: 99%

General relativistic simulations of magnetized binary neutron star mergers

et al. 2008

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Binary neutron stars (NSNS) are expected to be among the leading sources of gravitational waves observable by ground-based laser interferometers and may be the progenitors of short-hard gamma ray bursts. We present a series of general relativistic NSNS coalescence simulations both for unmagnetized and magnetized stars. We adopt quasiequilibrium initial data for circular, irrotational binaries constructed in the conformal thin-sandwich (CTS) framework. We adopt the BSSN formulation for evolving the metric and a high-resolution shock-capturing scheme to handle the magnetohydrodynamics. Our simulations of unmagnetized binaries agree with the results of Shibata, Taniguchi and Uryū [1]. In cases in which the mergers result in a prompt collapse to a black hole, we are able to use puncture gauge conditions to extend the evolution and determine the mass of the material that forms a disk. We find that the disk mass is less than 2% of the total mass in all cases studied. We then add a small poloidal magnetic field to the initial configurations and study the subsequent evolution. For cases in which the remnant is a hypermassive neutron star, we see measurable differences in both the amplitude and phase of the gravitational waveforms following the merger. For cases in which the remnant is a black hole surrounded by a disk, the disk mass and the gravitational waveforms are about the same as the unmagnetized cases. Magnetic fields substantially affect the long-term, secular evolution of a hypermassive neutron star (driving 'delayed collapse') and an accretion disk around a nascent black hole.

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“…As Faber et al [27] have pointed out, the inversion from conservative to primitive hydrodynamic variables is only possible if S ≡ g ij S i S j < S max ≡ τ (τ + 2D). After each evolution step, we impose the condition S ≤ S code max = f S max .…”

Section: Code Improvementsmentioning

confidence: 99%

Equation of state effects in black hole–neutron star mergers

Duez¹,

Foucart²,

Kidder³

et al. 2010

Class. Quantum Grav.

130

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Abstract. The merger dynamics of a black hole-neutron star (BHNS) binary is influenced by the neutron star equation of state (EoS) through the latter's effect on the neutron star's radius and on the character of the mass transfer onto the black hole. We study these effects by simulating a number of BHNS binaries in full general relativity using a mixed pseudospectral/finite difference code. We consider several models of the neutron star matter EoS, including Γ = 2 and Γ = 2.75 polytropes and the nuclear-theory based Shen EoS. For models using the Shen EoS, we consider two limits for the evolution of the composition: source-free advection and instantaneous β-equilibrium. To focus on EoS effects, we fix the mass ratio to 3:1 and the initial aligned black hole spin to a/m = 0.5 for all models. We confirm earlier studies which found that more compact stars create a stronger gravitational wave signal but a smaller postmerger accretion disk. We also vary the EoS while holding the compaction fixed. All mergers are qualitatively similar, but we find signatures of the EoS in the waveform and in the tail and disk structures.

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Relativistic hydrodynamics in the presence of puncture black holes

Cited by 38 publications

References 72 publications

Magnetorotational collapse of very massive stars to black holes in full general relativity

Magnetorotational collapse of very massive stars to black holes in full general relativity

General relativistic simulations of magnetized binary neutron star mergers

Equation of state effects in black hole–neutron star mergers

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