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

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

QuickTime™ and aPNG decompressor

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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

2H

(adiabatic EOS)

Sheets swallow stripes (H > RL):

Simplified Sheet Structure

(Crab) only if- sheets survive? 9

(protons)

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

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?

Parallel E in Pulsar return currents

Pulsed Gamma Rays: Acceleration in Boundary layer along open field lines

QuickTime™ and aTIFF (Uncompressed) decompressor

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QuickTime™ and aTIFF (Uncompressed) decompressor

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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)