Structure and evolution
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Structure and Evolution. of Pulsar Wind Nebulae. Take In:. Pulsars are born as reservoirs of tremendous rotational energy Their strong magnetic fields and rapid rotation rates promote loss of rotational energy through formation of a relativistic magnetized wind

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Structure and evolution

Structure and Evolution

of Pulsar Wind Nebulae

Patrick Slane MODE SNR/PWN Workshop


Take in

Take In:

  • Pulsars are born as reservoirs of tremendous rotational energy

  • Their strong magnetic fields and rapid rotation rates promote loss of

  • rotational energy through formation of a relativistic magnetized wind

  • Particles from that wind eventually merge into the ISM. Pulsars thus

  • convert rotational energy into diffuse relativistic particle energy in the ISM

How can we possibly follow the conversion of a rotational energy

exceeding 1031 erg cm-3 to its ultimate fate as a particle energy

density comprising a tiny fraction of 1 eV cm-3? (Hint: It isn’t easy,

and still far from perfect…)

Patrick Slane MODE SNR/PWN Workshop


Jet torus structure in pwne

Jet/Torus Structure in PWNe

  • Anisotropic flux with

  • maximum energy flux

  • in equatorial zone

  • - radial particle outflow

  • - striped wind from

  • Poynting flux

  • decreases away

  • from equator

  • - Wind in nebula is

  • particle-dominated

van den Heuvel 2006

Patrick Slane MODE SNR/PWN Workshop


Jet torus structure in pwne1

Jet/Torus Structure in PWNe

  • Anisotropic flux with

  • maximum energy flux

  • in equatorial zone

  • - radial particle outflow

  • - striped wind from

  • Poynting flux

  • decreases away

  • from equator

  • - Wind in nebula is

  • particle-dominated

Lyubarsky 2002

Patrick Slane MODE SNR/PWN Workshop


Jet torus structure in pwne2

Jet/Torus Structure in PWNe

Crab

  • Polar jets form

  • - subject to kink

  • instabilities

  • - outflow speeds > 0.2c

  • (e.g. Gaensler et al. 2002)

  • Anisotropic flux with

  • maximum energy flux

  • in equatorial zone

  • - radial particle outflow

  • - striped wind from

  • Poynting flux

  • decreases away

  • from equator

  • - Wind in nebula is

  • particle-dominated

  • - Doppler beaming

  • indicates torus flows

  • with v > 0.4c (e.g., Lu

  • et al. 2001)

Seward et al. 2006

G54.1+0.3

Lu et al. 2001

Vela

Patrick Slane MODE SNR/PWN Workshop

Pavlov et al. 2003


Jet torus structure in pwne3

Jet/Torus Structure in PWNe

Crab

  • Polar jets form

  • - subject to kink

  • instabilities

  • - outflow speeds > 0.2c

  • (e.g. Gaensler et al. 2002)

  • Anisotropic flux with

  • maximum energy flux

  • in equatorial zone

  • - radial particle outflow

  • - striped wind from

  • Poynting flux

  • decreases away

  • from equator

  • - Wind in nebula is

  • particle-dominated

  • - Doppler beaming

  • indicates torus flows

  • with v > 0.4c (e.g., Lu

  • et al. 2001)

Seward et al. 2006

G54.1+0.3

pulsar axis

Begelman & Li 1992

Lu et al. 2001

3C 58

  • Magnetic tension in

  • equatorial plane results

  • in elongation along

  • rotation axis

Slane et al. 2004

Patrick Slane MODE SNR/PWN Workshop


Jet torus structure in pwne4

Jet/Torus Structure in PWNe

Crab

  • Polar jets form

  • - subject to kink

  • instabilities

  • - outflow speeds > 0.2c

  • (e.g. Gaensler et al. 2002)

  • Anisotropic flux with

  • maximum energy flux

  • in equatorial zone

  • - radial particle outflow

  • - striped wind from

  • Poynting flux

  • decreases away

  • from equator

  • - Wind in nebula is

  • particle-dominated

  • - Doppler beaming

  • indicates torus flows

  • with v > 0.4c (e.g., Lu

  • et al. 2001)

Hester et al. 2008

G54.1+0.3

pulsar axis

Begelman & Li 1992

Lu et al. 2001

3C 58

  • Magnetic tension in

  • equatorial plane results

  • in elongation along

  • rotation axis

Slane et al. 2004

Patrick Slane MODE SNR/PWN Workshop


Pwne and their snrs

PWNe and Their SNRs

Reverse Shock

PWN Shock

Forward Shock

Pulsar

Termination

Shock

Pulsar Wind

Unshocked Ejecta

Shocked Ejecta

Shocked ISM

PWN

ISM

  • Pulsar

  • - injects particles and Poynting flux

  • Pulsar Wind

  • - sweeps up ejecta; shock decelerates

  • flow, accelerates particles; PWN forms

  • Supernova Remnant

  • - sweeps up ISM; reverse shock heats

  • ejecta; ultimately compresses PWN; energy distribution of particles in nebula tracks

  • evolution; instabilities at PWN/ejecta interface may allow particle escape

Gaensler & Slane 2006

Patrick Slane MODE SNR/PWN Workshop


Example g292 0 1 8

Example: G292.0+1.8

Park et al. 2007

Red: O Lya, Ne Hea

Orange: Ne Lya

Green: Mg Hea

Blue: Si Hea, S Hea

4.0-7.0 keV

Chandra/ACIS

Patrick Slane MODE SNR/PWN Workshop


Example g292 0 1 81

Example: G292.0+1.8

Park et al. 2007

Red: O Lya, Ne Hea

Orange: Ne Lya

Green: Mg Hea

Blue: Si Hea, S Hea

Lee et al. 2010

Chandra/ACIS

  • X-rays reveal shocked wind from

  • massive progenitor star

Patrick Slane MODE SNR/PWN Workshop


Pwn evolution

PWN Evolution

see Gelfand et al. 2009

energy input and swept-up

ejecta mass

PWN evolution

Patrick Slane MODE SNR/PWN Workshop


Pwn evolution1

PWN Evolution

energy input and swept-up

ejecta mass

Vorster et al. 2013

PWN evolution

Patrick Slane MODE SNR/PWN Workshop


Evolution of pwn emission

Evolution of PWN Emission

  • Spin-down power is injected into the

  • PWN at a time-dependent rate

  • Assume input spectrum (e.g., PL):

  • - note that studies of Crab and other

  • PWNe suggest that there may be

  • multiple components

  • Get associated synchrotron and IC emission from electron population in the

  • evolved nebula

  • - combined information on observed spectrum and system size provide

  • constraints on underlying structure and evolution

Patrick Slane MODE SNR/PWN Workshop


Evolution of pwn emission1

Evolution of PWN Emission

  • Spin-down power is injected into the

  • PWN at a time-dependent rate

  • Assume input spectrum (e.g., PL):

  • - note that studies of Crab and other

  • PWNe suggest that there may be

  • multiple components

  • Get associated synchrotron and IC emission from electron population in the

  • evolved nebula

  • - combined information on observed spectrum and system size provide

  • constraints on underlying structure and evolution

Patrick Slane MODE SNR/PWN Workshop


Evolution of pwn emission2

Evolution of PWN Emission

  • Spin-down power is injected into the

  • PWN at a time-dependent rate

  • Assume input spectrum (e.g., PL):

  • - note that studies of Crab and other

  • PWNe suggest that there may be

  • multiple components

1000 yr

2000 yr

5000 yr

CMB

inverse

Compton

synchrotron

  • Get associated synchrotron and IC emission from electron population in the

  • evolved nebula

  • - combined information on observed spectrum and system size provide

  • constraints on underlying structure and evolution

Patrick Slane MODE SNR/PWN Workshop


Injection from relativistic shocks

Injection from Relativistic Shocks

Spitkovsky 2008

  • PIC simulations of particle acceleration in relativistic shocks show build-up

  • of energetic particles (Spitkovsky 2008)

  • Multi-component input spectrum: Maxwellian + power law

  • – and possibly more complex if conditions differ at different acceleration sites

Patrick Slane MODE SNR/PWN Workshop


Pwn structure evolution 3c 58

PWN Structure & Evolution: 3C 58

Slane et al. 2008

Slane et al. 2004

  • Thermal X-rays evident from shocked ejecta

  • (Bocchino et al. 2001; Slane et al. 2004)

  • Spectrum of torus indicates complex injection

  • spectrum (Slane et al. 2008)

  • - evidence of position-dependent acceleration?

Patrick Slane MODE SNR/PWN Workshop


Pwn structure evolution snr 0540 69

PWN Structure & Evolution: SNR 0540-69

  • Multi-l studies reveal 0-rich ejecta,

  • bright PWN, young pulsar, expanding

  • SNR shell

  • Broadband spectrum shows evolutionary

  • break

  • - disconnect in X-rays complicates

  • interpretation; may indicate complex

  • injection spectrum

CXO

Kaaret et al. 2001

Mignani et al. 2012

Patrick Slane MODE SNR/PWN Workshop


G21 5 0 9

Matheson & Safi-Harb 2005

CXO

G21.5-0.9

  • X-rays reveal SNR shell and PWN with

  • compact core and (Slane et al. 2000)

  • - shell from dust scattering, DSA, and

  • ejecta (Bocchino et al. 2005)

  • - radio observations identify young, faint

  • pulsar (Camilo et al. 2006)

36 arcsec

Patrick Slane MODE SNR/PWN Workshop


G21 5 0 91

Matheson & Safi-Harb 2005

CXO

G21.5-0.9

  • X-rays reveal SNR shell and PWN with

  • compact core and (Slane et al. 2000)

  • - shell from dust scattering, DSA, and

  • ejecta (Bocchino et al. 2005)

  • - radio observations identify young, faint

  • pulsar (Camilo et al. 2006)

  • PWN and torus detected in IR

  • - Broadband spectrum of torus shows

  • evidence of structure between IR and X-ray

Spitzer 24/8 mm

Patrick Slane MODE SNR/PWN Workshop


G21 5 0 92

G21.5-0.9

  • X-rays reveal SNR shell and PWN with

  • compact core and (Slane et al. 2000)

  • - shell from dust scattering, DSA, and

  • ejecta (Bocchino et al. 2005)

  • - radio observations identify young, faint

  • pulsar (Camilo et al. 2006)

  • PWN and torus detected in IR

  • - Broadband spectrum of torus shows

  • evidence of structure between IR and X-ray

  • [Fe II] 1.64 mm image shows shocked

  • ejecta surrounding PWN

  • Polarization in IR indicates magnetic field

  • with toroidal geometry

[Fe II] 1.64 mm

Zajczyk et al. 2012

Ks linear-polarized intensity

Patrick Slane MODE SNR/PWN Workshop


Rs interactions g327 1 1 1

RS Interactions: G327.1-1.1

  • G327.1-1.1 is a composite SNR

  • for which radio morphology

  • suggests PWN/RS interaction

t = 20,000 yr

high r

low r

Blondin et al. 2001

Patrick Slane MODE SNR/PWN Workshop

Temim et al. 2009


Rs interactions g327 1 1 11

prings

RS Interactions: G327.1-1.1

prongs

cometary

structure

tail

pulsar + torus?

Patrick Slane MODE SNR/PWN Workshop

Temim et al. 2009


Rs interactions g327 1 1 12

RS Interactions: G327.1-1.1

prongs

cometary

structure

tail

pulsar + torus?

Radio

Simulation

Patrick Slane MODE SNR/PWN Workshop

Temim et al. 2009


Rs interactions msh 15 56

RS Interactions: MSH 15-56

Temim et al. 2013

  • Radio observations reveal shell with

  • bright, flat-spectrum nebula in center

  • - no pulsar known, but surely a PWN

  • - nebula significantly displaced from SNR

  • center

  • X-ray studies show thermal shell w/

  • very faint hard emission near PWN

  • - pulsar candidate seen as hard point source

  • w/ faint X-ray trail extending to PWN

Patrick Slane MODE SNR/PWN Workshop


Rs interactions msh 15 561

RS Interactions: MSH 15-56

Temim et al. 2013

  • Radio observations reveal shell with

  • bright, flat-spectrum nebula in center

  • - no pulsar known, but surely a PWN

  • - nebula significantly displaced from SNR

  • center

Patrick Slane MODE SNR/PWN Workshop


Rs interactions msh 15 562

RS Interactions: MSH 15-56

  • X-ray spectrum gives n0 ≈ 0.1 cm-3

  • SNR/PWN modeling gives t ≈ 12 kyr

  • - SNR reverse shock has completely

  • disrupted PWN

  • Fermi observations of MSH 15-56 may

  • be consistent with emission from an

  • evolved PWN

  • - if correct, pulsar has essentially departed

  • relic PWN and is injecting particles into

  • newly-forming nebula

  • - additional observations required to better

  • constrain ambient density and ejecta mass

Temim et al. 2013

Patrick Slane MODE SNR/PWN Workshop


Vela x an evolved pwn

Vela X: An Evolved PWN

LaMassa et al. 2008

de Jager et al. 2008

pulsar

wind

ejecta

cocoon

pulsar

Radio

PWN

Patrick Slane MODE SNR/PWN Workshop


Structure and evolution

Vela X: An Evolved PWN

  • TeV emission observed concentrated

  • along cocoon

  • - GeV emission observed throughout

  • PWN, but brightest region is offset

  • from TeV peak

Fermi LAT

contours

Hinton et al. 2011

H.E.S.S.

contours

  • TeV peak may be recent injection into

  • cocoon following RS interaction

  • - older energetic particles may have

  • been lost to diffusion; however…

Patrick Slane MODE SNR/PWN Workshop


Structure and evolution

Vela X: An Evolved PWN

hard emission

at Fermi LAT

peak

Fermi LAT

contours

H.E.S.S.

contours

Re-acceleration of low energy electrons, producing GeV IC peak and flat X-ray spectrum?

nonthermal emission hard

along cocoon, but soft

in eastern PWN as expected

from synchrotron losses

Patrick Slane MODE SNR/PWN Workshop


Take away

Take Away

  • Pulsars are born as reservoirs of tremendous rotational energy

  • Their strong magnetic fields and rapid rotation rates promote loss of

  • rotational energy through formation of a relativistic magnetized wind

  • Particles from that wind eventually merge into the ISM. Pulsars thus

  • convert rotational energy into diffuse relativistic particle energy in the ISM

  • The magnetic/particle pulsar wind is axisymmetric and particle-dominated.

  • It creates a nebula that drives itself through the interior of its host SNR.

  • - The particle spectrum is complicated. This affects the multi-l spectrum.

  • The evolution of the wind nebula is strongly affected by that of its surrounding

  • SNR, particularly the mass of its ejecta, and the density of its surroundings.

  • - Early evolution can be dominated by massive radiative losses. Late evolution

  • can be dominated by asymmetric crushing of nebula. This may increase

  • diffusive escape of particles.

  • Our models for PWN evolution can be directly tied to phenomena that we

  • can image, and spectral evolution that we can resolve. The picture is still

  • evolving, but we are clearly on the right track.

Patrick Slane MODE SNR/PWN Workshop


Summary

Summary

  • Multiwavelength studies of PWNe reveal:

  • - spin properties of central engines

  • - geometry of systems

  • - spatially-resolved spectra

  • - interaction with supernova ejecta

  • - presence of freshly-formed dust

  • These lead to constraints on:

  • - particle acceleration in relativistic shocks

  • - formation of jets

  • - physics of pulsar magnetospheres

  • - nature of progenitor stars

  • - early and late-phase evolution of pulsar winds

  • Current advances are being made across the electromagnetic spectrum,

  • as well as in theoretical modeling, and point the way for investigations

  • in virtually every wavelength band.

Patrick Slane MODE SNR/PWN Workshop


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