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Multiple Sheet Beam Instability of Current Sheets in Striped Relativistic Winds Jonathan Arons

Multiple Sheet Beam Instability of Current Sheets in Striped Relativistic Winds Jonathan Arons University of California, Berkeley. 1. latitude sector. As if energy flux. in a narrow. Crab Vela. G54.1 J2229.

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Multiple Sheet Beam Instability of Current Sheets in Striped Relativistic Winds Jonathan Arons

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  1. Multiple Sheet Beam Instability of Current Sheets in Striped Relativistic Winds Jonathan Arons University of California, Berkeley 1

  2. latitude sector As if energy flux in a narrow Crab Vela G54.1 J2229 B1706 J0538 Rings and Torii Ng & Romani Torii in rotational equator - small aspect ratio - /r ~ 0.1(Crab), smaller in others 2

  3. , nebular response ~ images Magic: If Poynting Flux dominated wind strongest toward equator “Unmagnetized” equatorial channel (Komisssarov & Lyubarsky 2003; del Zanna et al 2004; Bogovalov et al 2005)

  4. Outer Wind Properties, : Like Split Monopole of Aligned Rotator Without Dissipation: Current Sheet, carries return current Relativistic Beam: “protons” (i=0), e- (i=p) Sheet Opening Angle: 4

  5. PSR i Equatorial Current Sheet Frozen-in wave 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 5

  6. i=9o i=60o Inner Wind: Magnetically Striped Force Free Simulation of i=60o Rotator (Spitkovsky) Current Sheet Separating Stripes (Bogovalov) 6

  7. 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.) Insufficient Current? (everybody) sheet strong waves? - Melatos-vacuum) 7

  8. Other Effects Leading to Dissipation: Toroidal Sheets: kink instability, growth rate ~ c/r ~ expansion rate - slow? saturates at nonlinear kink, then tearing? MHD detonation - explosive growth of ballooning modes, creates small scale turbulence - perhaps applies if wind acceleration large 8

  9. Stream Instability of Multiple Sheets Current sheets = transmission lines Current = 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 channel 9

  10. Simplified Sheet Structure 2H (adiabatic EOS) Sheets swallow stripes (H > RL): (Crab) only if (protons) - sheets survive? 10

  11. Sheets Interact - Two Stream (Weibel-like) instability x0=RL<< r Thin Sheet (krL<<1) dynamics as if each sheet is unmagnetized although intersheet medium MHD x0 11

  12. Imagine Magnetic disturbance at each sheet - Alfven pol Two Symmetric Sheet Instability j0 x force compresses each sheet’s surface density into filaments parallel to j0 Surface current filaments reinforce - Weibel instability in flatland RL Growth Rate 2 symmetric sheets = purely growing in proper frame 12

  13. Proper Growth Rate (vA=c, vbeam=c, sheet thickness = ) Growth rate > expansion rate for 13

  14. Saturation - Magnetic Trapping beam particles scattered by self fields 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 14

  15. Anomalous Resistivity in Sheets - rapid expansion of sheets, destruction of intersheet field? (Coroniti’s model) Resistive electric field in sheet - equilibrium beam energy (?) Anomalous resistance, scattering: radiation (synchroton), sheets radiate - pulsed emission? (Kirk et al; historically, JA) Many sheets, sheet strength j0 declines with r: radiation of long wavelength EM waves (fast modes shocks) of relativistic amplitude?

  16. Conclusion(?) Asymptotically low s due to dissipation, sheets don’t survive even to Rm = current starvation radius, never mind to termination shock Dissipation broadens sheets much faster than in adiabatic expansion (sheet beams much denser than Coroniti’s sheets) - if stripe death due to anomalous resistivity, rate may decline as sheets broaden?; - reconnection (tearing modes, drift-kink,....) maintains high dissipation rate (shortens length scale along B0 directions) - conversion to strong waves (and surfing acceleration) exists? competes with/exceeds resistive dissipation? Inner wind (r << Rm) creates observable synchrotron emission from sheets, observable pulses? Or, steady emission? (low level unpulsed emission exists) 16

  17. Jets - striped jets exist? (Konigl, Spruit) - related dissipation mechanisms 17

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