Radiation- -Dominated Dominated Radiation Relativistic Current - - PowerPoint PPT Presentation

Radiation Radiation-

• Dominated

Dominated Relativistic Current Sheets Relativistic Current Sheets

C.

• C. Jaroschek

Jaroschek and and M. Hoshino

• M. Hoshino

University of Tokyo University of Tokyo

Relativistic Current Sheet Instabilities

VA ~ c, T/mc2 > 1, Electron and Positron Plasmas

Reconnection Mode Drift Kink Mode Z X Y Z

10-3 10-2 10-1 100 10-2 10-1 100 101 102

RMR RDK

Magnetic Energy Dissipation Rate (c)

T0/mc2

DK-mode MRX

Open issue for relativistic Current Sheet

• radiation effect such as synchrotron cooling

2 2 14 2

/ 1 10 10                         mc E B G

c dyn dyn loss

  

e.g. Magnetor, Pulsar magnetosphere,…

10-2 100 102 104 106 108 1010 1012 1014 1016 100 101 102 103 104 105 106 107 108 E/mec2 accc=1 accc=102

Synchrotron Radiation Effect

ε N(ε) Without radiation loss N(ε) ε

P

Synchrotron Loss

With radiation loss

Fast Reconnection

Radiation Loss Effect in PIC Simulation Code

Abraham-Lorentz Formula for Radiation Drag Force

Radiation Loss Effect in PIC Simulation Code

Abraham-Lorentz Formula for Radiation Drag Force

τ0 : Light crossing time over classical electron radius (e^2/mc^2)/c ~ 10^‐23 s

Main Radiation Effect is Synchrotron Radiation (cf. Noguchi et al. 2005)

Time Evolution of MR & DKI

α=0 α=10-12 α=10-11 Tearing Drift-Kink No Radiation Loss Intermediate Dominant Radiation Loss

Growth Curves

Tearing Mode (Reconnection) Drift-Kink Mode

α: radiation loss coefficient (α=0 : No radiation loss, α=10-10 : Strong radiation loss)

Comparison of Growth Rate

Relativistic Tearing Mode Relativistic Drift-Kind Mode

Super-Fast Reconnection strong weak (radiation cooling) Normalized Growth Rate

Reason for Fast Growth

• Decrease of gas pressure by radiation loss
• Shrink of plasma sheet & thin plasma sheet
• Temperature Anisotropy T// ≠ T⊥

Why reconnection has super-fast growth?

Temperature Anisotropy (Early Stage)

3

• 3

3 3

• 3

3 3

• 3

3

• 3

3 1 2

• 2
• 1

large T⊥ synchrotron cooling synchrotron cooling Y X

Linear Growth Rate (Γ) under Temperature Anisotropy

• Tearing Mode

– strong dependence on T⊥/T// (e.g. Chen et al., 1984) – T⊥> T//  Γ increase – T⊥< T//  Γ decrease

• Drift-Kink Mode

– weak dependence on T⊥/T//

T⊥/T//  isotropization

Late Nonlinear Stage

α=0 α=10-12 α=10-11 Tearing Drift-Kink

Temperature Anisotropy in Late Nonlinear Stage

T⊥< T//

reconnection suppressed, shifted to small k mode Y X

• 3
• 2
• 1

3 2 1 Y Y Y

Relativistic Reconnection under Synchrotron Cooling

Initial State Early Stage Late Stage T⊥> T// T⊥< T// kλ~O(1)

k-1 λ

kλ<<1

Sweet-Parker-Type

Summary

• Relativistic Reconnection with Radiation Cooling

– thin current sheet due to radiation cooling – fast growth of reconnection/drift-kink instability

• Nonlinear Evolution of Reconnection/Drift-Kink

– Early Stage: T⊥> T//

• Super-Fast Reconnection
• Fast Drift-Kink Instability (weak effect of Temp. Anisotropy)

– Late Nonlinear Stage: T⊥< T//

• Transition to Sweet-Parker Reconnection