25/03/22 Variable Galactic Gamma-Ray Sources , Heidelberg, Germany 1 Maxim Barkov MPI-K, Heidelberg, Germany Space Research Institute, Russi University of Leeds, UK Serguei Komissarov University of Leeds, UK Accretion/Blandford-Znajeck processes and jet formation
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Maxim Barkov MPI-K, Heidelberg, Germany Space Research Institute, Russia, University of Leeds, UK
Accretion/Blandford-Znajeck processes and jet formation. Maxim Barkov MPI-K, Heidelberg, Germany Space Research Institute, Russia, University of Leeds, UK Serguei Komissarov University of Leeds, UK. Blandford-Znajek mechanism. - PowerPoint PPT Presentation
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In the last few years we can see significant progress in general relativistic magneto hydrodynamics (GRMHD) simulations of BH accretion systems. It reveals a flow structure that can be decomposed into a disk, corona, disk wind and highly magnetized polar region that contains the jet (De Villiers, Hawley and Krolik 2003; Hawley and Krolik 2006; McKinney and Gammie 2004; McKinney 2005, 2006, 2007; McKinney and Balndford 2009; Shibata, Sekiguchi and Takahashi, 2007, Barkov and Komissarov 2008, 2010, Barkov and Baushev 2011).
• 2D axisymmetric GRMHD;• Kerr-Schild metric;• Realistic EOS;• Neutrino cooling;• Starts at 1s from collapse onset. Lasts for < 1s
Rotation:
rc=6.3x103kml0 = 1017 cm2 s-1
230 1,/minsin crrll
III. Numerical simulations
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Free fall model of collapsing star (Bethe, 1990)
radial velocity:
mass density:
accretion rate:
Gravity: gravitational field of Black Hole only (Kerr metric); no self-gravity;Microphysics: neutrino cooling ; realistic equation of state, (HELM, Timmes & Swesty, 2000); dissociation of nuclei (Ardeljan et al., 2005); Ideal Relativistic MHD - no physical resistivity (only numerical);
1
2/11
1 1011.0
sM
M
M
s
tCM sun
sun
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magnetic field lines, and velocity vectors
unit length=4.5km t=0.24s
Model:AC1=9; Bp=3x1010 G
log10 (g/cm3) log10 P/Pmlog10 B/Bp
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magnetic field lines, and velocity vectors
unit length=4.5km t=0.31s
Model:AC1=9; Bp=3x1010 G
log10 (g/cm3)
7Variable Galactic Gamma-Ray Sources ,
Heidelberg, Germany
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Model:AC1=9; Bp=3x1010 G
log10 (g/cm3)
magnetic field lines
8Variable Galactic Gamma-Ray Sources ,
Heidelberg, Germany
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Model:CC1=3; Bp=1010 G
velocity vectors
log10 P/Pm
9Variable Galactic Gamma-Ray Sources ,
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Jets are powered mainly by the black hole via the Blandford-Znajek mechanism !!
• No explosion if a=0; • Jets originate from the black hole;• ~90% of total magnetic flux is accumulated by the black hole;• Energy flux in the ouflow ~ energy flux through the horizon (disk contribution < 10%);• Theoretical BZ power:
Different magnetic field topologies:Dipole, quadruple 1 and quadruple 2.
The initial conditions consist of an equilibrium torus (Fishbone and Moncrief 976; Abramowicz et al. 1978; Komissarov 2006), which is a "torus" of plasma with a black hole at the center. The value of the specific angular momentum of matter and angular momentum of BH ‘a’ determines the total effective potential.
Time evolution of magnetic flux of model Quadruple 2 on horizon, t=0.00496 sec -- solid,t=0.0248 sec -- dashed, t=0.1238 sec -- doted, t=0.4452 sec -- three dots dashed.
Time evolution of magnetic flux of Dipole model on radius r=4.7 rg left panel and on horizon central panel, t=0.00496 sec -- solid,t=0.0248 sec -- dashed, t=0.0495 sec -- dot dashed, t=0.0991 sec -- doted, t=0.346 sec -- three dots dashed.