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2007-01-182007- 01-18 The Evolution & Structure of Pulsar Wind Nebulae Gaensler, B. M., & Slane P.O. ARA&A, 2006, 44:17
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2 Observational : Gaensler, B. M., & Slane P.O. ARA&A, 2006, 44:17Observational : Gaensler, B. M., & Slane P.O. ARA&A, 2006, 44:17 Theoretical : Reynolds & Chevalier, 1984, ApJ, 278:630Theoretical : Reynolds & Chevalier, 1984, ApJ, 278:630 (RC84) Swaluw, et al., 2004, A&A, 420:937; Chevalier, 2005, ApJ, 619:839 References
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3 SNR => pulsar-driven SNR => PWN Prototype: Crab
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4 The Prototype—Crab nebula SN 1054 Central star 16m pulsar P=33 ms Pdot=36 ns/day Edot~5*10^38 erg/s L~3*10^38 erg/s Pulsar-driven wind nebula
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5 Theoreticall Theoretically Marvelous testing ground for studying –Relativistic flows and their interactions with surrounding –Shocks –Pulsar itself –Mechanisms of high v birth kicks of pulsars –etc.
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6 Theory of pulsar & radiation Spin-down –Edot –n –Age –B Evolution –P(t) –Edot(t) Crab (Pacini & Salvati 1973) (Manchester & Taylor 1973)
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7 Goldreich & Julian 1969 Kennel & Coroniti 1984a,b Bogovalov & Khangoulyan 2002 Bogovalov et al. 2005 Pulsar Wind-magnetodynamic
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8 Emission & Spectra of nebulae Radio: X-ray: Synchrotron (Ginzburg & Syrovatskii, et al., 1965)
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9 Emission & Spectra of nebulae (Ginzburg & Syrovatskii, et al., 1965) ν r expected increase:Δα = 0.5, <typically observed Δαinferred at low ν high B Steepening of spectrum with time: Relic breaks in the spectrum can be produced by a rapid decline in the pulsar output over time, and these breaks propagate to lower frequencies as the PWN ages (Pacini & Salvati 1973). Steepening of spectrum with radius: … (Kennel & Coroniti 1984) –Mixing of electrons of different ages at each radius? diffusion?
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10 The nature of this spectral steepening is not understood; theory above is based on a simple pow-law assumption. Rapid decline of injection ( inherent spectrum deviate from power-law?), modifications from discrete acceleration sites, all contribute to a complicated integrated spectrum. “As a result, the interpretation of spectral steepening as being due to synchrotron losses can lead to drastically wrong conclusions about PWN properties.” Emission & Spectra of nebulae
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11 Observationally Detailed structrues: Crab especially 40-50 PWN Category: –Composite (with a shell-like SNR) –Crab-like –Cometary (pulsar with high v, few) Evolution Evolution
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12 Evolution Phase I: t<τ, expand into homogeneous ejecta –Phase II(if sweep core slow ejecta all up): constant-mass shell Phase III : t>= τ,Edot down Phase IV: reverse shock pass (theoretical, eg., RC84)
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13 Evolution Phase I – Expanding into Unshocked Ejecta Phase II – Interact with SNR Reverse Shock Phase III – Inside a Sedov Shock Phase IV – Pulsar in Interstellar Gas
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14 Phase I – Expanding into Unshocked Ejecta
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15 Phase I
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16 Chevalier, 1977 RC84
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19 Wind Termination shock γ>~10^6 Bpwn ~ 300 μG (Crab) Bpwn ~ 80 μG (3C58)
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20 Torus, Jet, Wisp & Filament
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21 Torus σ P y ~ 0.25 pc (Bogovalov & Khangoulyan 2002, 2005)
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22 Theory: Invisible in standard model Observation: visible! kink instabilities in the toroidal field accelerate particles limit collimation curved jets a wide variation in fraction of Edot considerable differences in the additional acceleration efficiency Jet
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23 Enhancement on Torus Doppler beaming & relativistic effect Crab: v ~ c/3 (0.2c – 0.6c) φ~ 30 deg. I near /I far ~ 5 (Pelling, et al., 1987)
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24 G54.1+0.3: luminosity, geometry Puzzles (Lu et al., 2002)
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25 Crab: –inner ring (uniform) –variable knots (~months) unstable quasi-stationary shocks outside the termination shock at high latitudes ( large σ small shock radius) (Komissarov & Lyubarsky 2004) Puzzles
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26 G320.4-1.2
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27 Wisp (Koji Mori, 2002) ACIS-S3 (11/3/2000- 4/6/2001) v ~ 0.5c (Heter et al. 2002)
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28 Variation nature: unveiled –Synchrotron instabilities –Cmpression of e/e + pair plasma (~0.15 pc) Radio structures (VLA) similar to optical/X-ray accelerate in the same region as for the X-ray emitting population (Bietenholz et al. 2004) Wisp
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29 Optical: –R-T instabilities as the expanding relativistic bubble sweeps up and accelerates slower moving ejecta (Hester et al. 1996) –simulation 60-75% mass concerntration (eg.,Jun 1998) Filaments
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30 Radio: –Expanding PWN encounters filaments, compress & increase n & B enhance synchrotron emission (Jun 1998, Bucciantini et al. 2004) No X-ray: –High energy electron suffer synchrotron loss Filaments
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31 X-ray filaments of 3C58: associated with radio, not with optical different mechanism -magnetic loops torn from the toroial field by kink instabilities Filaments
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32 Phase II – Interact with SNR Reverse Shock
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33 Phase II Phase III
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34 Phase III – Inside a Sedov Shock
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35 Phase II Phase III
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36 Phase IV – Pulsar in Interstellar Gas
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37 Phase III Phase IV
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38 V PSR ~ 400-500 km/s, 1000 km/s Bow shock & Cometary PWN
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39 Very young pulsar & PWN –Crab, 3C58(1181?), SN1987A, SN1986J Winds from highly magnetized NS TeV Observations of PWN –Crab (Weekes et al. 1989, etc.) Pulsar Winds in Binary Systems –Double pulsar PSR J0737-3039 –PSR B1957+20, PSR B1259-63 Other & Recent results
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41 Thank you for your attention!
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