Structure and Evolution of Pulsar Wind Nebulae Patrick

Structure and Evolution of Pulsar Wind Nebulae Patrick Slane MODE SNR/PWN Workshop Orsay, France (6/19/2013)

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 e. V cm-3? (Hint: It isn’t easy, and still far from perfect…) Patrick Slane MODE SNR/PWN Workshop Orsay, France (6/19/2013)

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 Orsay, France (6/19/2013)

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 Orsay, France (6/19/2013)

Jet/Torus Structure in PWNe Crab • Anisotropic flux with maximum energy flux in equatorial zone - radial particle outflow - striped wind from Poynting flux decreases away from equator • Polar jets form - subject to kink instabilities - outflow speeds > 0. 2 c (e. g. Gaensler et al. 2002) Seward et al. 2006 G 54. 1+0. 3 Lu et al. 2001 - Wind in nebula is particle-dominated Vela - Doppler beaming indicates torus flows with v > 0. 4 c (e. g. , Lu et al. 2001) Patrick Slane et Workshop al. 2003 MODEPavlov SNR/PWN Orsay, France (6/19/2013)

Jet/Torus Structure in PWNe Crab • Anisotropic flux with maximum energy flux in equatorial zone - subject to kink instabilities - outflow speeds > 0. 2 c (e. g. Gaensler et al. 2002) Seward et al. 2006 G 54. 1+0. 3 pulsar axis - radial particle outflow - striped wind from Poynting flux decreases away from equator • Polar jets form Lu et al. 2001 Begelman & Li 1992 - Wind in nebula is particle-dominated - Doppler beaming indicates torus flows with v > 0. 4 c (e. g. , Lu et al. 2001) Patrick Slane 3 C 58 Slane et al. 2004 MODE SNR/PWN Workshop • Magnetic tension in equatorial plane results in elongation along rotation axis Orsay, France (6/19/2013)

Jet/Torus Structure in PWNe Crab • Anisotropic flux with maximum energy flux in equatorial zone - subject to kink instabilities - outflow speeds > 0. 2 c (e. g. Gaensler et al. 2002) Hester et al. 2008 G 54. 1+0. 3 pulsar axis - radial particle outflow - striped wind from Poynting flux decreases away from equator • Polar jets form Lu et al. 2001 Begelman & Li 1992 - Wind in nebula is particle-dominated - Doppler beaming indicates torus flows with v > 0. 4 c (e. g. , Lu et al. 2001) Patrick Slane 3 C 58 Slane et al. 2004 MODE SNR/PWN Workshop • Magnetic tension in equatorial plane results in elongation along rotation axis Orsay, France (6/19/2013)

PWNe and Their SNRs ISM Shocked Ejecta Shocked ISM Unshocked Ejecta Pulsar Termination Shock PWN Pulsar Wind PWN Shock Reverse Shock Forward Shock • Pulsar - injects particles and Poynting flux • Pulsar Wind - sweeps up ejecta; shock decelerates flow, accelerates particles; PWN forms Gaensler & Slane 2006 • 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 Patrick Slane MODE SNR/PWN Workshop Orsay, France (6/19/2013)

Example: G 292. 0+1. 8 Park et al. 2007 Red: O Lya, Ne Hea Chandra/ACIS 4. 0 -7. 0 ke. V Orange: Ne Lya Green: Mg Hea Blue: Si Hea, S Hea Patrick Slane MODE SNR/PWN Workshop Orsay, France (6/19/2013)

Example: G 292. 0+1. 8 Park et al. 2007 Red: O Lya, Ne Hea Chandra/ACIS Orange: Ne Lya Green: Mg Hea Blue: Si Hea, S Hea Patrick Slane MODE SNR/PWN Workshop Lee et al. 2010 • X-rays reveal shocked wind from massive progenitor star Orsay, France (6/19/2013)

PWN Evolution see Gelfand et al. 2009 energy input and swept-up ejecta mass PWN evolution Patrick Slane MODE SNR/PWN Workshop Orsay, France (6/19/2013)

PWN Evolution energy input and swept-up ejecta mass Vorster et al. 2013 PWN evolution Patrick Slane MODE SNR/PWN Workshop Orsay, France (6/19/2013)

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 Orsay, France (6/19/2013)

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 Orsay, France (6/19/2013)

Evolution of PWN Emission • Spin-down power is injected into the PWN at a time-dependent rate 1000 yr 2000 yr 5000 yr • Assume input spectrum (e. g. , PL): - note that studies of Crab and other PWNe suggest that there may be multiple components synchrotron CMB inverse Compton • 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 Orsay, France (6/19/2013)

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 Orsay, France (6/19/2013)

PWN Structure & Evolution: 3 C 58 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 Orsay, France (6/19/2013)

PWN Structure & Evolution: SNR 0540 -69 • Multi-l studies reveal 0 -rich ejecta, bright PWN, young pulsar, expanding SNR shell CXO • Broadband spectrum shows evolutionary break - disconnect in X-rays complicates interpretation; may indicate complex injection spectrum Kaaret et al. 2001 Mignani et al. 2012 Patrick Slane MODE SNR/PWN Workshop Orsay, France (6/19/2013)

Matheson & Safi-Harb 2005 CXO G 21. 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 Orsay, France (6/19/2013)

Matheson & Safi-Harb 2005 CXO G 21. 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 Orsay, France (6/19/2013)

G 21. 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 Zajczyk et al. 2012 • [Fe II] 1. 64 mm image shows shocked ejecta surrounding PWN • Polarization in IR indicates magnetic field with toroidal geometry Ks linear-polarized intensity Patrick Slane MODE SNR/PWN Workshop Orsay, France (6/19/2013)

RS Interactions: G 327. 1 -1. 1 • G 327. 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 Temim et al. 2009 MODE SNR/PWN Workshop Orsay, France (6/19/2013)

RS Interactions: G 327. 1 -1. 1 prongs cometary structure tail prings pulsar + torus? Patrick Slane Temim et al. 2009 MODE SNR/PWN Workshop Orsay, France (6/19/2013)

RS Interactions: G 327. 1 -1. 1 prongs cometary structure tail pulsar + torus? Radio Patrick Slane Temim et al. 2009 MODE SNR/PWN Workshop Simulation Orsay, France (6/19/2013)

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 • 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 Orsay, France (6/19/2013)

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 Orsay, France (6/19/2013)

RS Interactions: MSH 15 -56 • X-ray spectrum gives n 0 ≈ 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 Orsay, France (6/19/2013)

Vela X: An Evolved PWN La. Massa et al. 2008 pulsar wind ejecta cocoon pulsar Radio PWN Patrick Slane MODE SNR/PWN Workshop de Jager et al. 2008 Orsay, France (6/19/2013)

Vela X: An Evolved PWN Fermi LAT contours • Te. V emission observed concentrated along cocoon - Ge. V emission observed throughout PWN, but brightest region is offset from Te. V peak Hinton et al. 2011 H. E. S. S. contours • Te. V 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 Orsay, France (6/19/2013)

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 Ge. V 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 Orsay, France (6/19/2013)

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 Orsay, France (6/19/2013)

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 Orsay, France (6/19/2013)