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Into the Engine: GRMHD Simulations. Jonathan McKinney Stanford/KIPAC. Black Hole Accretion Systems. 10 38 erg/s M~10M ¯. 10 52 erg/s M~3M ¯. 10 44 erg/s M~10 7 M ¯. Mirabel & Rodriguez (Sky & Telescope, 2002). GRB Jets. Issues: Launch:  -  vs. MHD Jets Jet: Fireball vs. EM

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into the engine grmhd simulations

Into the Engine:GRMHD Simulations

Jonathan McKinney

Stanford/KIPAC

black hole accretion systems
Black Hole Accretion Systems

1038erg/s

M~10M¯

1052erg/s

M~3M¯

1044erg/s

M~107M¯

Mirabel & Rodriguez (Sky & Telescope, 2002)

grb jets
GRB Jets
  • Issues:
  • Launch: - vs. MHD Jets
  • Jet: Fireball vs. EM
  • Prompt: Shocks vs. EM dissipation

Taylor et al. 2004

Fireball Model (Sari, Piran, Meszaros, Rees >1993)

EM Model (Lyutikov & Blandford 2003)

agn jets
AGN Jets

M87

Junor/Biretta/Walker

  • Jet Issues:
  • Some Dark (non-dissipative?)
  • Origin of FRI vs. FRII Classes?
  • Radio Loud-Quiet Dichotomy?
  • Blazars (-ray and TeV Emission?)
  • Implication for GRBs?

Pictor A

Mrk501

Cygnus-A

3C31

example solutions to agn dichotomy
Example Solutions to AGN Dichotomy
  • Changes in Field Geometry
    • Non-Dipolar Fields (Beckwith/McKinney ‘09)
  • Changes in Jet Confinement
    • Triggers Magnetic Switch (Meier et al. ’97, Komissarov 2009)
  • Variation in amount of BH/Disk Magnetic Flux
    • Flux trapping (Reynolds 06, Garafalo ‘09)
    • Magnetically-dominated disk (Igumenshchev ‘09)
    • Difference in Disk Thickness (Meier ’01)
  • Application to GRBs? (flux trapping: Proga ‘06)
bh x ray binaries
BH X-Ray Binaries

Belloni et al.

Orosz

Mirabel & Rodriguez

  • Questions:
  • What determines the Spectral (and Temporal) States?
  • How are X-ray binary states related to AGN and GRBs?
disk jet coupling effects
Disk-Jet Coupling Effects
  • Role of Large-Scale vs. Small-Scale Magnetic Fields?
  • Disk dominates BH in powering jet?(Ghosh & Abramowicz 1997;Livio, Ogilvie, Pringle 1999)
  • Weak Magnetic Field Threads BH?(Ghosh & Abramowicz 1997;Livio, Ogilvie, Pringle 1999)
  • Jet Power / a2 (weak dependence)? (Blandford & Znajek 1977 vs. McKinney 2005)

MacDonald & Thorne ‘82

BZ77

Blandford & Payne ‘82

3d grmhd simulations
3D GRMHD Simulations
  • Issues:
  • Jet from Disk or BH?
  • Unstable to Turbulence in Disk?
  • Unstable to Accreting Disordered Field?

Quadrupolar

Dipolar

slide9

Quadrupolar Field Jet Fails

  • Magnetic field geometry crucially determines existence of jet

Fully 3D GRMHD Jet Simulations

McKinney & Blandford (2009)

slide10

Dipolar Field Jet Succeeds

  • Suggests jets require accretion of organized field

Fully 3D GRMHD Jet Simulations

McKinney & Blandford (2009)

x ray binaries origin of states

Quadrupolar

Dipolar

X-Ray Binaries: Origin of States?

No Ordered Field

Igumenshchev (2009) McKinney & Blandford (2009)

slide12

Poynting Jet

“Matter” Jet

BH Engine Flow Structure

CORONA: MA~EM

FUNNEL: EM dominated

JETS: Unbound, outbound flow

McKinney & Gammie (2004)

DeVilliers, Hawley, Krolik (2003-2004)

field becomes super equipartition for high spin
Field becomes super-equipartition for high spin

Komissarov & McKinney (2007)

McKinney (2005)

Tchekhovskoy, Narayan, McKinney (2010)

jet propagation stability kink

z

B

RL

j

R

L

Jet Propagation Stability: Kink
  • |m|=1 most dangerous: Center-of-mass shifted
  • Kruskal-Shafranov non-rel. criterion
  • Tomimatsu (2001) ~rel. criterion
  • Narayan et al. (2009) rel. criterion
  • Expansion & Finite Mass-loading: Jet goes out of causal contact

McKinney (2006) Narayan et al. (2009)

slide15

Dipolar

Field

  • Dipolar Field Jet Succeeds:
  • Relativistic Rotation, Expansion, Non-linear Saturation
applications to grbs 1
Applications to GRBs 1
  • Setup:
  • Collapsar Model
  • 2D GRMHD
  • Start with BH and collapsing star
  • Realistic EOS
  • Neutrino Cooling (no heating)
  • Strong and Ordered Magnetic Field
  • Result:
  • BZ-effect drives MHD jet
  • Still no high Lorentz factors
  • 3D and resolution needed to study boundary instabilities

Komissarov & Barkov (2008-2009)

applications to grbs 2
Applications to GRBs 2

Problem:

  • Ultrarelativistic motion:  ~ 400 (Lithwick & Sari 2001, Piran 2005)
  • Afterglow Breaks: » 2-20
  • Standard MHD Jet Models give » 1

Any Resolution?

  • Stellar Break-Out Rarefaction

”Achromatic break” in the light curve when(µ)t≃1

Light curve modeling givesµ=2{10

100 days

1 day

10 days

Tchekhovskoy, Narayan, McKinney (2010)

jet break out
Jet Break-Out

0

2

3

1

log()

=100

µ =0.02

µ=2

=500

µ =0.04

µ=20

star

BH

BH

Tchekhovskoy, Narayan, McKinney (2010)

Komissarov et al. (2010)

effects of time variability
Effects of Time-Variability
  • Idea:
    • Time-variable Jet leads to magnetized jet bubble separated by a near-vacuum if envelope cannot relax fast enough to fill-in hole left by the jet
  • Problem:
    • Compact object + disk generate wind and fills-in hole when jet is turned off
    • No forward rarefaction would occur
  • Solution: Transient suppression of jet+wind by ram pressure of fresh in-falling material

Granot et al. (2010) & Lyutikov (2010)

grmhd simulations of thin disks

z

R

GRMHD Simulations of Thin Disks

Results:

1) Thin Disk theory (Novikov & Thorne 1973) holds fairly well as long as H/R. 0.07

2)  and shear stress not good indicators of dissipation or transport near ISCO or horizon

3) Assumed initial Magnetic Field controls level of deviations from Thin Disk Theory

PA

Shafee, McKinney, et al. (2008)

Penna, McKinney, et al. (2010)

review
Review:
  • BH Driven Jet becomes Relativistic if Ordered Field
    • GRB Jets: Stellar Break-out Leads to À 1 » 20
  • Disk Driven Wind-Jet is Weakly Relativistic
    • Mass-Loaded by Disk Turbulence
  • Jet Stability Maintained by (e.g.)
    • Relativistic Rotation of Field Lines & Expansion of Jet
    • Non-linear Saturation
  • Standard (Novikov-Thorne) Thin Disk theory holds
    • Much prior work on GRB accretion solutions are ~ valid