multiple sheet beam instability of current sheets in striped relativistic winds
DESCRIPTION
Multiple Sheet Beam Instability of Current Sheets in Striped Relativistic Winds Inertial Parallel E in Neutron Star Magnetospheres: Return Cuurent Sheets and Pulsed Gammas Jonathan Arons University of California, Berkeley. 1. latitude sector. As if energy flux. in a narrow. - PowerPoint PPT PresentationTRANSCRIPT
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Multiple Sheet Beam Instability ofCurrent Sheets in Striped Relativistic Winds
Inertial Parallel E in Neutron Star Magnetospheres:Return Cuurent Sheets and Pulsed Gammas
Jonathan AronsUniversity of California, Berkeley
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Crab Vela
G54.1 J2229
B1706 J0538
Ng & Romani
Torii in rotational equator - small aspect ratio - /r ~ 0.1(Crab), smaller
in others
Rings and Torii
As if energy flux in a narrow latitude sector
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Poynting Flux dominated wind strongest toward equator
Magic: If , nebular response ~ images
(Komisssarov & Lyubarsky 2003; del Zanna et al 2004; Bogovalov et al 2005)
“Unmagnetized” equatorial channel
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Outer Wind Properties,
:
Current Sheet, carries return current
Sheet Opening Angle:
Like Split Monopole of Aligned Rotator Without Dissipation:
Relativistic Beam: “protons” (i=0), e- (i=p)
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PSR i
Crab 80o
Vela 65o
1509-58 60o
1706-44 40o
0630+17 25o
1055+08 70o
Observed PSR = oblique rotators
Gamma Ray PSR, i from Romani and Yadigarglou outer gap model
Equatorial Current Sheet Frozen-in wave,Striped wind
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Striped Jets: Spruit, Konigl
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Force Free Simulation of i=60o Rotator (Spitkovsky)
Current Sheet Separating Stripes (Bogovalov)
i=60o i=9o
Inner Wind: Magnetically Striped
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Stripe Dissipation If wrinkled current dissipates, striped field dissipates, magnetic energy coverts to flow kinetic energy, “heat” & high frequency radiation, strong waves - partition?
Sheet Dissipation: Tearing of one locally ~ plane sheet? (Coroniti; too slow? - Kirk & co.)Cause: Current starvation? (everybody)sheet strong waves? - Melatos-vacuum)
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Stream Instability of Multiple Sheets
Current sheets = transmission linesCurrent = charged particle beam
injected by source - Y or X line at LC
| | =IGJ=Goldreich-Julian Current
In absence of dissipation, beams flow adiabatically in narrow channel8
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2H
(adiabatic EOS)
Sheets swallow stripes (H > RL):
Simplified Sheet Structure
(Crab) only if- sheets survive? 9
(protons)
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Sheets Interact - Two Stream (Weibel-like) instability
Thin Sheet (krL<<1) dynamics as if each sheet is unmagnetizedalthough intersheet medium MHD
x0 =RL<< r
x0
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Two Symmetric Sheet Instability
Imagine Magnetic
disturbance at each sheet - Alfven pol
j0 x force compresseseach sheet’s surface density into filamentsparallel to j0
Surface current filamentsreinforce -Weibel instability in flatland
RL
Growth Rate 2 symmetric sheets = purely growing in proper frame
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Proper Growth Rate (vA=c, vbeam=c, sheet thickness = )
Growth rate > expansion rate for
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Saturation - Magnetic Trappingbeam particles scattered by
self fields
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Growth & Trapping Saturation of Spatially Distributed Weibel (Spitkovsky & JA)
shock - transient growth and decay; current sheet is driven but end result will “always” be magnetic turbulence that scatters particles
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Anomalous Resistivity in Sheets - rapid expansion
of sheets, destruction of intersheet field? (Coroniti’s model)
Resistive electric field in sheet - equilibrium beam energy (?)
Many sheets, sheet strength j0 declines with r: radiation oflong wavelength EM waves (fast modes shocks) ofrelativistic amplitude?
Anomalous resistance, scattering: radiation (synchroton), sheets radiate - pulsed emission? (Kirk et al; historically, JA)
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Experiments
Computational: 3D PIC, must be MHD between sheets (frozen-in pairs) resolve current layer: Larmor and c/p scales of beam particles
could use rectangular geometry
Lab Experiment?Use laser on dense slab to launch relativistic electron-positron plasma
onto field lines of reversed B (RFP?)Launch beams into field reversal region?
Laser generated MHD electron-positron plasmaX XCharged
particle beam
currents
Strong Background B
Perp E to give cross field plasma flow?
Expt improves on simulation?
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Parallel E in Pulsar return currents
Pulsed Gamma Rays: Acceleration in Boundary layer along open field lines
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Return Current Sheet
Gamma rays radiated by some sort of sheet at or near the boundary layer
Romani’s “outer gap” surface: quasi-vacuum E accelerator
: thickness ~ rl(RL)(r/RL)3/2
Return current, precipitating plasma formed by reconnection at RY
Return current density huge: Jret ~ J[RL/rl(RL)] ~ J (e/mc2) >>>1magnetospheric potential = B*R*(R*/RL)2: 1012-1017 V
EP ~
3vP
r p2 J P
(ret) ~ 2
8πκ ret
rParticle inertia in the current channel:
κret = pair multiplicity, precipitating from Y-line, < 104
Y-line at r = RY
~ RL
Simulations? Experiments (Earth’s auroral currents, magnetotail reconnection informative)