Fund. Physics & Astrophysics of Supernova Remnants Lecture #1 What SNRs are and how are they observed Hydrodynamic evolution on shell-type SNRs Microphysics in SNRs – electron-ion equ Lecture #2 Microphysics in SNRs - shock acceleration Statistical issues about SNRs Lecture #3 Pulsar wind nebulae Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Order-of magn. estimates SN explosion Mechanical energy: Ejected mass: VELOCITY: Ambient medium Density: Mej~Mswept when: SIZE: AGE: Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

“Classical” Radio SNRs Spectacular shell-like morphologies compared to optical polarization spectral index (~ – 0.5) BUT Poor diagnostics on the physics featureless spectra (synchrotron emission) acceleration efficiencies ? Tycho – SN 1572 Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

A view of Galactic Plane 90cm Survey 4.5 < l < 22.0 deg (35 new SNRs found; Brogan et al. 2006) Blue: VLA 90cm Green: Bonn 11cm Red: MSX 8 mm Radio traces both thermal and non-thermal emission Mid-infrared traces primarily warm thermal dust emission Brogan et al 2006, ApJ 639, L25 Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

SNRs in the X-ray window Probably the “best” spectral range to observe Thermal: measurement of ambient density Non-Thermal: synchrotron-emitting electrons are near the maximum energy (synchrotron cutoff) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

X-ray spectral analysis Low-res data Overall fit with thermal models High-res data Abundances of elements Single-line spectroscopy! Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Shell-type SNR evolution a “classical” (and wrong) scenario Isotropic explosion and further evolution Homogeneous ambient medium Three phases: Linear expansion Adiabatic expansion Radiative expansion Isotropic Homogeneous Linear Adiabatic Radiative Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Basic concepts of shocks Hydrodynamic (MHD) discontinuities Quantities conserved across the shock Mass Momentum Energy Entropy Jump conditions (Rankine-Hugoniot) Independent of the detailed physics shock r V Strong shock If Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Forward and reverse shocks Density Radius Reverse shock Forward Shock: into the CSM/ISM (fast) Reverse Shock: into the Ejecta (slow) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Dimensional analysis and Self-similar models Dimensionality of a quantity: Dimensional constants of a problem If only two, such that M can be eliminated, THEN evolution law follows immediately! Reduced, dimensionless diff. equations Partial differential equations (in r and t) then transform into total differential equations (in a self-similar coordinate). Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Early evolution Linear expansion only if ejecta behave as a “piston” Ejecta with and Ambient medium with and Dimensional parameters and Expansion law: Chevalier 1982, ApJ 258, 790 Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

A self-similar model Deviations from “linear” expansion (Chevalier 1982) Deviations from “linear” expansion Radial profiles Ambient medium Forward shock Contact discontinuity Reverse shock Expanding ejecta Chevalier 1982, ApJ 258, 790 Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Evidence from SNe VLBI mapping (SN 1993J) Decelerated shock For an r -2 ambient profile ejecta profile is derived Bartel et al 2002, ApJ 581, 404 (SN1993J) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

The Sedov-Taylor solution After the reverse shock has reached the center Middle-age SNRs swept-up mass >> mass of ejecta radiative losses are negligible Dimensional parameters of the problem Evolution: Self-similar, analytic solution (Sedov,1959) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

The Sedov profiles Most of the mass is confined in a “thin” shell Density Temperature Pressure Most of the mass is confined in a “thin” shell Kinetic energy is also confined in that shell Most of the internal energy in the “cavity” Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Thin-layer approximation Layer thickness Total energy Dynamics Correct value: 1.15 !!! Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

What can be measured (X-rays) from spectral fits … if in the Sedov phase Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Testing Sedov expansion Tycho SNR (SN 1572) Dec.Par. = 0.47 Deceleration parameter SN 1006 Dec.Par. = 0.34 Required: RSNR/D (angular size) t (reliable only for historical SNRs) Vexp/D (expansion rate, measurable only in young SNRs) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Other ways to “measure” the shock speed Radial velocities from high-res spectra (in optical, but now feasible also in X-rays) Electron temperature from modelling the (thermal) X-ray spectrum Modelling the Balmer line profile in non-radiative shocks (see below) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

End of the Sedov phase Sedov in numbers: When forward shock becomes radiative: with Numerically: Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Beyond the Sedov phase When t>ttr, energy no longer conserved. What is left? “Momentum-conserving snowplow” (Oort 1951) WRONG !! Rarefied gas in the inner regions “Pressure-driven snowplow” (McKee & Ostriker 1977) Kinetic energy Internal energy Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Numerical results 2/5 0.33 2/7=0.29 1/4=0.25 ttr (Blondin et al 1998) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

An analytic model Thin shell approximation Analytic solution Bandiera & Petruk 2004 Thin shell approximation Analytic solution H either positive (fast branch) limit case: Oort or negative (slow branch) limit case: McKee & Ostriker H, K from initial conditions Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Inhomogenous ambient medium Circumstellar bubble (ρ ~ r -2) evacuated region around the star SNR may look older than it really is Large-scale inhomogeneities ISM density gradients Small-scale inhomogeneities Quasi-stationary clumps (in optical) in young SNRs (engulfed by secondary shocks) Thermal filled-center SNRs as possibly due to the presence of a clumpy medium Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Collisionless shocks Coulomb mean free path High Mach numbers Collisional scale length (order of parsecs) Larmor radius is much smaller (order of km) High Mach numbers Mach number of order of 100 MHD Shocks B in the range 10-100 μG Complex related microphysics Electron-ion temperature equilibration Diffusive particle acceleration Magnetic field turbulent amplification Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Electron & Ion equilibration Naif prediction, for collisionless shocks But plasma turbulence may lead electrons and ion to near-equilibrium conditions Coulomb equilibration on much longer scales (Cargill and Papadopoulos 1988) (Spitzer 1978) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Optical emission in SN1006 “Pure Balmer” emission in SN 1006 Here metal lines are missing (while they dominate in recombination spectra) Extremely metal deficient ? Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

“Non-radiative” emission Emission from a radiative shock: Plasma is heated and strongly ionized Then it efficiently cools and recombines Lines from ions at various ionization levels In a “non-radiative” shock: Cooling times much longer than SNR age Once a species is ionized, recombination is a very slow process WHY BALMER LINES ARE PRESENT ? Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

The role of neutral H Scenario: shock in a partially neutral gas (Chevalier & Raymond 1978, Chevalier, Kirshner and Raymond 1980) Scenario: shock in a partially neutral gas Neutrals, not affected by the magnetic field, freely enter the downstream region Neutrals are subject to: Ionization (rad + coll) [LOST] Excitation (rad + coll) Balmer narrow Charge exchange (in excited lev.)Balmer broad Charge-exchange cross section is larger at lower vrel Fast neutral component more prominent in slower shocks Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

H-alpha profiles MEASURABLE QUANTITIES Intensity ratio (Hester, Raymond and Blair 1994) (Kirshner, Winkler and Chevalier 1987) Cygnus Loop MEASURABLE QUANTITIES Intensity ratio Displacement (not if edge-on) FWHM of broad component (Ti !!) FWHM of narrow component (T  40,000 K – why not fully ionized?) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

SNR 1E 0102.2-7219 Very young and bright SNR in the SMC (Hughes et al 2000, Gaetz et al 2000) Very young and bright SNR in the SMC Expansion velocity (6000 km s-1, if linear expansion) measured in optical (OIII spectra) and in X-rays (proper motions) Electron temperature ~ 0.4-1.0 keV, while expected ion T ~ 45 keV Very small Te/Ti, or Ti much less than expected? Missing energy in CRs? Optical Radio X-rays Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Rino Bandiera, OAA. Fundamental Physics & Astrophysics of SNRs Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Lectures #2 & #3 Shock acceleration Pulsar Wind Nebulae The prototype: SN 1006 Physics of shock acceleration Efficient acceleration and modified shocks Pulsar Wind Nebulae The prototype: the Crab Nebula Models of Pulsar Wind Nebulae Morphology of PWN in theory and in practice A tribute to ALMA Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

The “strange case” of SN1006 Tycho with ASCA Hwang et al 1998 “Standard” X-ray spectrum Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Thermal & non-thermal Power-law spectrum at the rims Thermal spectrum in the interior Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Diffusive shock acceleration X flow speed Fermi acceleration Converging flows Particle diffusion (How possible, in a collisionless plasma?) Particle momentum distribution where r is the compression ratio (s=2, if r = 4) Synchrotron spectrum For r = 4, power-law index of -0.5 Irrespectively of diffusion coefficient (in the shock reference frame) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

The diffusion coefficient Diffusion mean free path (magnetic turbulence) (η > 1) Diffusion coefficient Reynolds 1998 Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

…and its effects Acceleration time Maximum energy Cut-off frequency Naturally located near the X-ray range Independent of B Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Basics of synchrotron emission Emitted power Characteristic frequency Power-law particle distribution If then Synchrotron life time Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

SN 1006 spectrum Rather standard ( -0.6) power-law spectrum in radio (-0.5 for a classical strong shock) Synchrotron X-rays below radio extrapolation Common effect in SNRs (Reynolds and Keohane 1999) Electron energy distribution: Fit power-law + cutoff to spectrum: “Rolloff frequency” Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Measures of rolloff frequency SN 1006 (Rothenflug et al 2004) Azimuthal depencence of the break Changes in tacc? or in tsyn? η of order of unity? Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Dependence on B orientation? Highly regular structure of SN 1006. Barrel-like shape suggested (Reynolds 1998) Brighter where B is perpendicular to the shock velocity? Direction of B ? Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Radio – X-ray comparison (Rothenflug et al 2004) Similar pattern (both synchrotron) Much sharper limb in X-rays (synchrotron losses) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Evidence for synchrotron losses of X-ray emitting electrons (Rothenflug et al 2004) Evidence for synchrotron losses of X-ray emitting electrons X-ray radial profile INCONSISTENT with barrel-shaped geometry (too faint at the center) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

3-D Geometry. Polar Caps? Polar cap geometry: electrons accelerated Ordered magnetic field (from radio polarization) Polar cap geometry: electrons accelerated in regions with quasi-parallel field (as expected from the theory) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Statistical analysis Expected morphologies in radio Polar cap SNR (Fulbright & Reynolds 1990) Expected morphologies in radio Barrel-like SNR (under various orientations) Polar cap SNR (under various orientations) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

The strength of B ? Difficult to directly evaluate the value of the B in the acceleration zone. νrolloff is independent of it ! “Measurements” of B must rely on some model or assumption Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Very sharp limbs in SN 1006 Chandra ASCA Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

B from limb sharpness Profiles of resolved non-thermal X-ray (Bamba et al 2004) Profiles of resolved non-thermal X-ray filaments in the NE shell of SN 1006 Length scales  1” (0.01 pc) upstream  20” (0.19 pc) downstream Consistent with B ~ 30 μG Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

A diagnostic diagram Acceleration time tacc = 270 yr Derivation of the diffusion coefficients: u=8.9 1024 cm2s-1 d=4.2 1025 cm2s-1 (Us=2900 km s-1) to compare with Bohm=(Emaxc/eB)/3 rolloff tsync> tacc  > Bohm Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Non-linear shock acceleration Such high values of B are not expected in the case of pure field compression (3-6 μG in the ISM, 10-20 μG in the shock – or even no compression in parallel shocks) Turbulent amplification of the field? Possible in the case of efficient shock acceleration scenario: particles, streaming upstream, excite turbulence (e.g. Berezhko; Ellison; Blasi) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Shock modification Dynamical effects of the accelerated particles onto the shock structure (Drury and Voelk 1981) Intrinsically non linear Shock precursor Discontinuity (subshock) Larger overall compression factor Accelerated particle distribution is no longer a power-law Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Deviations from Power-Law In modified shocks, acc. particles with different energies see different shock compression factors. Higher energy Longer mean free path Larger compress.factor Harder spectrum Concavity in particle distribution. (also for electrons) Thermal Blasi Solution Standard PL Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Gamma-ray emission Measurement of gamma-ray emission, produced by the same electrons that emit X-ray synchrotron, would allow one to determine the value of B. Synchrotron IC Radio X-ray γ-ray νFν Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Need for “targets” (molecular cloud?) On the other hand, there is another mechanism giving Gamma-ray emission accelerated ions p-p collisions pion production pion decay (gamma) Lower limit for B Need for “targets” (molecular cloud?) Efficiency in in accelerating ions? (The origin of Cosmic rays) (Ellison et al 2000) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

TeV telescopes generation H.E.S.S. Cherenkov telescopes Observations : RX J0852.0-4622 (Aharonian et al 2005) Upper limits on SN 1006 (Aharonian et al 2005) RX J1713.7-3946 (Aharonian et al 2006) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Observ. of RX J0852.0-4622 Good matching between X-rays and gamma-rays CO observation show the existence of a molecular cloud Pion-decay scenario slightly favoured. Nothing proved as yet Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Indirect tests on the CRs Some “model-dependent” side effects of efficient particle acceleration Forward and reverse shock are closer, as effect of the energy sink HD instabilities behavior depends on the value of eff (Decourchelle et al 2000) (Blondin and Ellison 2001) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Shock acceleration efficiency Theory predicts (~ high) values of the efficiency of shock acceleration of ions. Little is known for electrons Main uncertainty is about the injection process for electrons Shock thickness determined by the mfp of ions (scattering on magnetic turbulence) Electrons, if with lower T, have shorter mfps Therefore for them more difficult to be injected into the acceleration process Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

The Σ–D Relationship Empirical relation SNR surface brightness, in radio SNR diameter Any physical reason for this relation ? (Case & Bhattacharya 1998) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

A basic question Is the correlation representative of the evolution of a “typical object”? Or is, instead, the convolution of the evolution of many different objects? Theorists attempts to reproduce it. Berezhko & Voelk 2004 Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Dependence on ambient density (Berkhuijsen 1986) Primary correlations are D-n, and Σ-n Diff. ISM conditions Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Rino Bandiera, OAA. Fundamental Physics & Astrophysics of SNRs Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

The “Prototype” The Crab Nebula Optical Radio X-rays Thermal filaments Crab Nebula - radio The Crab Nebula Optical Thermal filaments Amorphous compon. Radio Filled-center nebula No signs of shell X-rays More compact neb. Jet-torus structure Crab Nebula – Ha + cont X-rays Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

The Crab Nebula spectrum (apart from optical filaments and IR bump) Synchrotron emission -0.8 -1.1 -0.3 -1.5 Radio Optical Soft X-rays Hard X-rays Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Some basic points Synchrotron efficiency Powered by the pulsar 10-20% of pulsar spin-down power Powered by the pulsar High polarizations (ordered field) No signs of any associated shell. Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Basics of synchrotron emission Emitted power Characteristic frequency Power-law particle distribution If then Synchrotron life time Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Simple modelling Homogeneous models (no info on structure) (Pacini & Salvati 1973) Homogeneous models (no info on structure) Magnetic field evolution Early phases (constant pulsar input) Later phases (most energy released) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Particle evolution (adiabatic vs synchrotron losses) Power-law injection With upper energy cutoff Continuum injection link to the pulsar spin down Particle evolution (adiabatic vs synchrotron losses) Evolutionary break Adiabatic regime (-0.3 in radio) Synchrotron-dominated regime (-0.8 in optical) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Kennel & Coroniti model (1984) Basics of “Pulsar Wind Nebula” scenario Pulsar magnetosphere Pulsar wind Termination shock Pulsar Wind Nebula Interface with the ejecta (CD, FS) Stellar ejecta Interface with the ambient medium (RS, CD, FS) Ambient medium (either ISM or CSM) Pulsar magnetosphere Pulsar wind Termination shock Pulsar Wind Nebula Stellar ejecta ISM Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

The ingredients Pulsar wind Termination shock super-relativistic magnetized (toroidal field) isotropic Termination shock mass conservation magnetic flux cons. momentum cons. energy cons. where (specific enthalpy) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Large and small σ limits weak shock flow stays super-relativistic neither field, nor density jump inefficient in converting kinetic into thermal energy Small σ strong shock flow braked to mildly relativistic speed both field and density increase kinetic energy efficienly converted Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

MHD evolution in the nebula Steady solution (flow timescale << SNR age) number flux cons. - magnetic flux cons. momentum cons. - energy cons. Asymptotic velocity !!! no solution for V∞=0 outer expansion Vext~1500 km s-1 (for the Crab Nebula) then σ~3 10-3 size of termination shock, from balance of wind ram pressure and nebular pressure Rn~10 arcsec (wisps region) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Radial profiles Inner part with: Outer part with: Equipartition in the outer part: Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Do we expect what observed? Injected particles power-law, between a min and a max energy only 1 free parameter (n2 and p2 from the jump conditions at the termination shock) plus wind parameters (L, σ and γ1 ) Energy evolution during radial advection Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Best-fit solution Parameters: Fit to: Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Rino Bandiera, OAA. Fundamental Physics & Astrophysics of SNRs Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Problems -Ia The sigma paradox A value is required, in order to get an effective slowing-down of the flow, and a high (10-20 %) synchrotron conversion efficiency BUT the (magnetically driven) pulsar wind cannot have been produced with a low σ . With a normal MHD evolution, the value of σ must keep constant from the acceleration region till the termination shock. Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Problems - Ib A POSSIBLE WAY OUT A tilted pulsar generates a striped wind. Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Problems -Ic Magnetic reconnection in the wind zone (if possible) would dissipate the field. (Coroniti 1990) Reconnection in the wind zone does not efficiently destroy the field. Reconnection at the termination shock is more effective. (Lyubarski & Kirk 1991) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Problems - IIa The unexpected radio emission Predicted radio flux is far lower (a factor ~100) than observed. No easy way to cure it. Little freedom on the particle number. Total power is fixed: more particles mean a lower γ1. Radio emitting electrons as a relict. Was the Crab much more powerful in the past? Ad hoc. All PWNe are radio emitters. Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Problems IIb Can it be “Diffusive synchrotron radiation”? (Fleishman & Bietenholz 2007) Turbulence spectral index ν. Theory only for a fully turbulent field Total spectrum is reproduced But observed polarization is not explained Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Non-spherical structure (Begelman & Li 1992) Particle, moving passively along field lines (flow motion assumed to be irrotational) Axisymmetric nebular field structure Steady state solutions Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

3C 58 MHD simulations van der Swaluw 2003 pulsar axis Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Elongated structures of PWNe pulsar spin G5.4-0.1 G11.2-0.3 Crab Nebula Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Details of the structure knot jet inner ring torus counter-jet Crab Nebula Vela Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Crab Nebula (Weisskopf et al 2000) Jet sizes Crab Nebula (Weisskopf et al 2000) 40” = 0.4 pc PSR B1509-58 (Gaensler et al 2002) 4’ = 6 pc 3C 58 (Slane et al. 2004) 13” = 0.2 pc 80” = 0.8 pc Vela Pulsar (Pavlov et al. 2003) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Simulating PWNe Relativistic MHD codes (Komissarov, 2006; Del Zanna et al 2004, 2006) Relativistic MHD codes Modelling a PWN like the Crab Velocity Magnetization Max Energy Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Surface brightness maps Jet-Torus structure Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Ingredients Wind parameters magnetization (still small, but not too much) σ~0.02 – 0.1 aaa wind anisotropy ( γeq~10 γpol ) “filling” the jets (since B = 0) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

PWN-ejecta interaction PWNe are confined by the associated shell-like SNR Not only the SNR is detectable (like in the Crab) In the Crab Nebula UV emission associated with a slow shock (against the SN ejecta)  ISM Shocked ISM Shocked Ejecta Unshocked Ejecta PWN Pulsar Wind Forward Shock Reverse Shock PWN Shock Pulsar Termination Shock Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Rino Bandiera, OAA. Fundamental Physics & Astrophysics of SNRs Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

A TRIBUTE TO ALMA SNRs and PWNs are mostly non-thermal in that spectral range. no use of spectral capabilities use of high spatial resolution, + wide field, + photometric stability (extended sources) Is mm-submm a “new band” for SNRs, or just an extension of the radio range? A study of the Crab Nebula (extension of a former work, Bandiera et al 2002) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

What has been done already Comparison of 1.3 mm (230 GHz) images (with IRAM 30-m telescope, 10” res) and radio (20 cm, VLA) maps Spectral map 230 GHz map -0.28 -0.20 Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

A further emission component Radio spectral index: -0.27 Concave spectral index from radio to mm Real effect or artifact? (absolute photometry) Evidence for an additional emission component Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Component B Image obtained optimizing the subtraction of amorphous part, and filaments, of radio image (PSF matched), with best-fit weights. Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

The subtracted components Amorphous component: consistent with an extension of the spectrum to mm, with the radio spectral index (-0.27). Filaments: consistent with spectral bending (νb~80 GHz). Morphologically, component B resembles more the Crab in the optical than in the radio (ALTHOUGH, in the mm range, electrons of Component B do not lose energy significantly by synchrotron). Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

The integrated spectrum Radio comp (A) Component B, with low freq cutoff. Evidence higher than from the error bar. Components A and B coexist in the optical. Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

Physical scenario Number of particles in Component B: Ntot ~ 2 1048. Consistent with Kennel & Coroniti) Filament magnetic fields ~6 times higher than the rest AND particle do not diffuse in/out of filaments (κ<100 κB). Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007

With ALMA The same analysis, with a resolution 100 times higher. Detailed mapping of Component B. Separation of comp A and B also through differences in the polarization patterns. Analysis of the spectral bending in individual filaments, and possibly even across the filament (B estimates). Mapping B in filaments (aligned? ordered?) Rino Bandiera, OAA Fundamental Physics & Astrophysics of SNRs SNA07, May 20-26, 2007