scholarly journals General Relativistic Collapse of Axially Symmetric Stars Leading to the Formation of Rotating Black Holes

1981 ◽  
Vol 65 (6) ◽  
pp. 1876-1890 ◽  
Author(s):  
T. Nakamura
Keyword(s):  
Black Holes ◽  
Axially Symmetric ◽  
Rotating Black Holes ◽  
General Relativistic ◽  
Relativistic Collapse

scholarly journals Plasmoid formation in global GRMHD simulations and AGN flares

2020 ◽  
Vol 495 (2) ◽  
pp. 1549-1565 ◽  
Author(s):  
Antonios Nathanail ◽  
Christian M Fromm ◽  
Oliver Porth ◽  
Hector Olivares ◽  
Ziri Younsi ◽  
...  
Keyword(s):  
Black Holes ◽  
Dipolar Field ◽  
Relativistic Jets ◽  
Poloidal Magnetic Field ◽  
Accretion Flows ◽  
Rotating Black Holes ◽  
General Relativistic ◽  
Formation And Evolution ◽  
Magnetohydrodynamic Simulations ◽  
Dissipation Processes

ABSTRACT One of the main dissipation processes acting on all scales in relativistic jets is thought to be governed by magnetic reconnection. Such dissipation processes have been studied in idealized environments, such as reconnection layers, which evolve in merging islands and lead to the production of ‘plasmoids’, ultimately resulting in efficient particle acceleration. In accretion flows on to black holes, reconnection layers can be developed and destroyed rapidly during the turbulent evolution of the flow. We present a series of two-dimensional general-relativistic magnetohydrodynamic simulations of tori accreting on to rotating black holes focusing our attention on the formation and evolution of current sheets. Initially, the tori are endowed with a poloidal magnetic field having a multiloop structure along the radial direction and with an alternating polarity. During reconnection processes, plasmoids and plasmoid chains are developed leading to a flaring activity and hence to a variable electromagnetic luminosity. We describe the methods developed to track automatically the plasmoids that are generated and ejected during the simulation, contrasting the behaviour of multiloop initial data with that encountered in typical simulations of accreting black holes having initial dipolar field composed of one loop only. Finally, we discuss the implications that our results have on the variability to be expected in accreting supermassive black holes.

Dragging of inertial frames by matter and waves

2021 ◽  
Author(s):  
Jiří Bičák ◽  
Tomáš Ledvinka
Keyword(s):  
Black Holes ◽  
Perturbation Theory ◽  
Inertial Frame ◽  
Cosmological Perturbation ◽  
Cosmological Perturbation Theory ◽  
Frame Dragging ◽  
Inertial Frames ◽  
Rotating Black Holes ◽  
Quantum Detection ◽  
General Relativistic

In this paper, we review and analyze four specific general-relativistic problems in which gravitomagnetism plays an important role: the dragging of magnetic fields around rotating black holes, dragging inside a collapsing slowly rotating spherical shell of dust, compared with the dragging by rotating gravitational waves. We demonstrate how the quantum detection of inertial frame dragging can be accomplished by using the Unruh–DeWitt detectors. Finally, we shall briefly show how “instantaneous Machian gauges” can be useful in the cosmological perturbation theory.

scholarly journals General relativistic plasmas around rotating black holes

2010 ◽  
Vol 6 (S275) ◽  
pp. 32-40 ◽  
Author(s):  
Shinji Koide
Keyword(s):  
Black Holes ◽  
Solar Flare ◽  
High Energy ◽  
Jet Formation ◽  
Relativistic Plasmas ◽  
Relativistic Jet ◽  
Rotating Black Holes ◽  
General Relativistic ◽  
Flare Model ◽  
The Ideal

AbstractWe show one of possible directions of general relativistic MHD (GRMHD) calculations of astrophysical relativistic jet formation. This was motivated by observations of radio knot ejections associated with high energy flares of an AGN in M87 and micro-quasars. We introduce a modified version of a solar flare model for the phenomenon. In the model, we have to consider a process beyond the ideal GRMHD. Especially, we focus on the special features of general relativistic plasmas around rotating black holes.

scholarly journals General Relativistic Collapse of an Axially Symmetric Star Leading to the Formation of Neutron Stars and Black Holes

1981 ◽  
Vol 93 ◽  
pp. 326-326 ◽  
Author(s):  
Takashi Nakamura ◽  
Kei-Ichi Maeda ◽  
Shoken Miyama ◽  
Misao Sasaki
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Density Distribution ◽  
Mass Density ◽  
Apparent Horizon ◽  
List Type ◽  
Metric Tensor ◽  
Proper Mass ◽  
General Relativistic ◽  
Relativistic Collapse

Using the [(2+1)+1]-dimensional representation of the Einstein equations, we have computed the general relativistic collapse of a rotating star. We adopt the cylindrical coordinate. The system is assumed to be axially and plane symmetric. The number of meshes is 28×28 in R and Z direction. The equation of state is P=1/3ρε for ρ< ρ*≡3×1014 g/cm3 and P=(ρ-ρ*)ε+1/3ρ*ε for We use the following initial conditions; ρ∝exp(-(R2+Z2)/λ), Ω∝exp(-R2/λ) where Ω and λ are angular velocity and a size parameter, respectively. We have calculated three models; (1)Model 1 M=10M⊙, ρc=3×1013g/cm3, α=0.20, β=0.05.(2)Model 2 M=10M⊙, ρc=3×1013g/cm3, α=0.20, β=0.12.(3)Model 3 M=10M⊙, ρc=3×1013g/cm3, α=0.20, β=0.22. where α=Eint/|Egrav| and β=Erot/|Egrav|. In all models, an apparent horizon was formed, that is, a black hole was formed. In Model 1, the final density distribution is oblate shape. In Model 2, there is a ringlike peak of the proper mass density distribution at the final stage. In Model 3, the determinant of the metric tensor goes to nearly zero at the ring in the equatorial plane, so that the proper mass density shows strong ringlike peak which is inside the apparent horizon. As the curvature invariant made from the Riemann tensor becomes very large at this ring, this may be a ring singularity of the space-time. These rotating black holes look like the Kerr black hole.

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