scholarly journals Exact general relativistic disks with magnetic fields

1999 ◽  
Vol 60 (10) ◽  
Author(s):  
Patricio S. Letelier
Keyword(s):  
Magnetic Fields ◽  
General Relativistic ◽  
Relativistic Disks

scholarly journals General relativistic simulations of black-hole–neutron-star mergers: Effects of magnetic fields

2012 ◽  
Vol 85 (6) ◽  
Author(s):  
Zachariah B. Etienne ◽  
Yuk Tung Liu ◽  
Vasileios Paschalidis ◽  
Stuart L. Shapiro
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Magnetic Fields ◽  
General Relativistic

scholarly journals Magnetorotational core collapse of possible GRB progenitors – I. Explosion mechanisms

2020 ◽  
Vol 492 (4) ◽  
pp. 4613-4634 ◽  
Author(s):  
M Obergaulinger ◽  
M Á Aloy
Keyword(s):  
Magnetic Fields ◽  
Time Scale ◽  
Main Sequence ◽  
Gamma Ray ◽  
Polar Axis ◽  
Hydrodynamic Instabilities ◽  
Alternative Description ◽  
Ram Pressure ◽  
General Relativistic ◽  
Relativistic Magnetohydrodynamics

ABSTRACT We investigate the explosion of stars with zero-age main-sequence masses between 20 and 35 M⊙ and varying degrees of rotation and magnetic fields including ones commonly considered progenitors of gamma-ray bursts (GRBs). The simulations, combining special relativistic magnetohydrodynamics, a general relativistic approximate gravitational potential, and two-moment neutrino transport, demonstrate the viability of different scenarios for the post-bounce evolution. Having formed a highly massive proto-neutron star (PNS), several models launch successful explosions, either by the standard supernova mechanism based on neutrino heating and hydrodynamic instabilities or by magnetorotational processes. It is, however, quite common for the PNS to collapse to a black hole (BH) within a few seconds. Others might produce proto-magnetar-driven explosions. We explore several ways to describe the different explosion mechanisms. The competition between the time-scales for advection of gas through the gain layer and heating by neutrinos provides an approximate explanation for models with insignificant magnetic fields. The fidelity of this explosion criterion in the case of rapid rotation can be improved by accounting for the strong deviations from spherical symmetry and mixing between pole and equator. We furthermore study an alternative description including the ram pressure of the gas falling through the shock. Magnetically driven explosions tend to arise from a strongly magnetized region around the polar axis. In these cases, the onset of the explosion corresponds to the equality between the advection time-scale and the time-scale for the propagation of Alfvén waves through the gain layer.

scholarly journals STEADY GENERAL RELATIVISTIC MAGNETOHYDRODYNAMIC INFLOW/OUTFLOW SOLUTION ALONG LARGE-SCALE MAGNETIC FIELDS THAT THREAD A ROTATING BLACK HOLE

2015 ◽  
Vol 801 (1) ◽  
pp. 56 ◽  
Author(s):  
Hung-Yi Pu ◽  
Masanori Nakamura ◽  
Kouichi Hirotani ◽  
Yosuke Mizuno ◽  
Kinwah Wu ◽  
...  
Keyword(s):  
Black Hole ◽  
Magnetic Fields ◽  
Large Scale ◽  
Rotating Black Hole ◽  
General Relativistic

scholarly journals GRMHD simulations of BH activation by small scale magnetic loops: Formation of striped jets and active coronae

2021 ◽  
Author(s):  
Anna Chashkina ◽  
Omer Bromberg ◽  
Amir Levinson
Keyword(s):  
Black Holes ◽  
Magnetic Fields ◽  
Current Sheet ◽  
Numerical Experiments ◽  
Small Scale ◽  
X Ray ◽  
Current Sheets ◽  
Cyclic Behaviour ◽  
General Relativistic ◽  
Equatorial Current

Abstract We have performed a series of numerical experiments aimed at studying the activation of Kerr black holes (BHs) by advection of small scale magnetic fields. Such configurations may potentially give rise to the formation of quasi-striped Blandford-Znajek jets. It can also lead to enhanced dissipation and generation of plasmoids in current sheets formed in the vicinity of the BH horizon, which may constitute a mechanism to power the hard X-ray emission seen in many accreting BH systems (a la lamppost models). Our analysis suggests that formation of quasi-striped jets with significant power may be possible provided loops with alternating polarity having sizes larger than ∼10rg or so can be maintained (either form sporadically or advected from outside) at a radius ≲ 102rg. This conclusion is consistent with recent results of general relativistic force-free simulations. We also find that the accretion dynamics exhibits cyclic behaviour in MAD states, alternating between high accretion phases and quenched accretion phases during which the magnetosphere becomes force-free out to radii ≳ 10rg. We suggest that such a behaviour should lead to notable variations of the observed luminosity and image of the inner disc (BH shadow image). Finally, we find that the transition between accreted loops on the BH gives rise to the formation of current sheets and energetic plasmoids on the jet boundary during intermittent periods when the jet becomes inactive, in addition to an equatorial current sheet that forms during peaks in the jet activity.

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