The Evolution & Structure of Pulsar Wind Nebulae

The Evolution & Structure of
2007-01-18
Pulsar Wind Nebulae
Gaensler, B. M., & Slane P.O.
ARA&A, 2006, 44:17

References
•Observational Observational : Gaensler, B. M., &
Slane P.O. ARA&A, 2006, 44:17
•Theoretical Theoretical : Reynolds & Chevalier,
1984, ApJ, 278:630 (RC84)
•Swaluw, et al., 2004, A&A, 420:937;
Chevalier, 2005, ApJ, 619:839

• SNR => pulsar-driven SNR => PWN
• Prototype: Crab

The Prototype— 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

Theoretically Theoreticall
• Marvelous testing ground for studying
– Relativistic flows and their
interactions with surrounding
– Shocks
– Pulsar itself
– Mechanisms of high v birth kicks of
pulsars
– etc.

Theory of pulsar & radiation
• Spin-down
– Edot
– n
– Age
– B
• Evolution
– P(t)
– Edot(t)
• Crab
(Manchester & Taylor 1973)
(Pacini & Salvati 1973)

Pulsar Wind-magnetodynamic
Wind magnetodynamic
• Goldreich & Julian 1969
• Kennel & Coroniti 1984a,b
• Bogovalov & Khangoulyan 2002
• Bogovalov et al. 2005

Emission & Spectra of nebulae
• Synchrotron
S
ν
ν −
∝
(Ginzburg & Syrovatskii, et al., 1965)
α
• Radio:
• X-ray:

Emission & Spectra of nebulae
• 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.”
1

Observationally
• Detailed structrues: Crab especially
• 40-50 PWN
• Category:
– Composite (with a shell-like SNR)
– Crab-like
– Cometary (pulsar with high v, few)
• Evolution
1

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
1

Phase I – Expanding into
Unshocked Ejecta
1

Phase I
1

•Chevalier, 1977
•RC84
1

Torus, Jet, Wisp & Filament
2

Jet
• 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
2

• G54.1+0.3: luminosity, geometry
(Lu et al., 2002)
Puzzles
2

G320.4-1.2
2

Wisp
ACIS-S3
(11/3/2000-
4/6/2001)
v ~ 0.5c
(Heter et al.
2002)
(Koji Mori,
2002)
2

Wisp
• 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)
2

• Optical:
Filaments
– 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)
2

• Radio:
Filaments
– 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
3

Filaments
• X-ray filaments of 3C58: associated with radio,
not with optical
different mechanism
-magnetic loops torn
from the toroial field
by kink instabilities
3

Phase II – Interact with
SNR Reverse Shock
3

Phase II
Phase III
3

Phase III – Inside a Sedov
Shock
3

Phase II
Phase III
3

Phase IV – Pulsar in
Interstellar Gas
3

Phase III
Phase IV
3

Bow shock & Cometary PWN
• V PSR ~ 400-500 km/s, 1000 km/s
3

Other & Recent results
• 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
3

Thank you for your attention!
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