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A New Aspect of the Crab Pulsar Nebula; Particle Acceleration and Heating Shibata, S., Tomatsuri, H., Shimanuki, M., Saito, K. Nakamura, Y., (Yamagata University) And Mori, K.(Pennsylvania State University) at Pusan National University, 2002 Nov. 18
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Previous View of the Crab Nebula 1 SN 1054 Synchrotron (Shklovskii 1953, Vashakidze 1954, Dombrovsky 1954) 33ms Pulsar; energy source (radio pulsar 1967; Hewish et al.1968; Staelin and Reifenstein 1968) L_rot = 5 x 10 38 erg/s
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Previous View of the Crab Nebula 2 Magnetic field; pulsar origin ; toroidal field (Aschenbach & Brinkmann 1975); Disc wind? Makishima et al. 1981
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Previous View of the Crab Nebula 3 Synchrotron Luminosity and spectrum R-Shock Equipartition field B ~ 0.2 mG γ ~10 6 Particle flux ~10 28 /s
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Previous View of the Crab Nebula 4 Kennel & Cornoniti 1984; acceleration efficiency of the wind = 99.7% Kinetic energy >> EM Energy Toroidal Field Ideal MHD EM KE Fast Shock B ~ 0.2 mG γ ~10 6 Particle flux ~10 28 /s = σ ~10 -3 EM KE
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Fig. 1 Spectral model with KC parameters. (Atoyan & Aharonian, 1996). If σ<<1, Plasma is heated and accelerated at the shock flow, and the nebula shines well. In the post shock flow, P gas >>P mag 、 sub-fast, flow speed down, field increases, so Bright at R_nebula ~ R_shock σ -1/2 Wind theory ( relativisitc Centrifugal wind ) σ<<1 mistery
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Chandra Observation -Disc and Jet -Wisp speed -Spatially resolved spectra Wisp velocity 0.45 c The kinetic-energy dominant wind shocks and shines Mori 2002
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This work If one extends the Kennel & Coroniti (KC) model to 3D, does one can understand the Chandra observation? (intuitively) the assumptions taken in KC model may be unjustified; the result of σ<<1 might also be unjustified. The nebula can be dissipative (acceleration and heating inside of the nebula
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A 3D model KC model Ideal-MHD (frozen-in) condition holds Toroidal field approximation Disc wind is assumed but
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log f [partcile /cm 3 /str] ε * = ε/mc 2 low energy particles → adiabatic loss high energy particles → synchrotron loss R * = 1.0 R * = 5.0 R * = 10.0 R * = 20.0R * = 30.0 synchrotoron burn-off energy Input parameter Lw = 5.0 × 10 38 erg/sec Rs = 3 × 10 17 cm γ w = u 1 = 3 × 10 6 (isotropic) We calculate f(γ) under the KC flow
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Volume emissivity j’ θ´ is the pitch angle of the particle which move towards us Doppler boost Intensity YZ plane = sky coordinate
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Suppose what kind of image ? Disc Wind is assumed, so ring? Due to Doppler boost in expanding flow, fore side is brighter ?
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Reproduced Image Lip-shaped; due to pure toroidal field (pitch angle effect) Turbulent field, magnitude of which is as same as roidal component !
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We need ~ 0.2 c flow with σ=0.003, v ~ 0.048 c Brightness Contrast ( 0.1-10.0 keV ) ( Weisskopf et al.2000) Reproduced image Contrast ~1.3 Contrast ~ 5.5
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Flow speed σ = 0.003 Magnetic Field σ = 0.003 distance Rs 10Rs distance Bright region should locate where flow is decelerated as far as ideal- MHD+σ<<1
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Reproduction of spectra (preliminary) (Mori 2002) (present work) Chandra observation 3D KC model Brightness Photon index Log I_ν Photon index
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Conclusion ( A New Aspect of the Crab Nebula comes out ) Spatially resolved spectra are reproduced well with the KC flow. Image is lip-shaped, indicating disordered field: far from pure toroidal Doppler boost does not account for brightness contrast between fore and back sides
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Stronger magnetic field and faster nebula flow σ=1-0.1 ; Magnetic reconnection ; high constrast fast flow (0.45c) then decelerated (Hester 2002) Discussion Not Lip, but Ring Disc is naturally formed
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A new model will be constracted ; dissipation of the magnetic field 3D modeling Thank you
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