1. The Theory of Supernova Remnants  Some comments on Supernova Remnants and the production of Cosmic Rays Don Ellison, North Carolina State University Tycho’s Supernova Remnant http://chandra.harvard.edu/photo/2005/tycho/ 10 20 eV Energy [eV] Flux 10 15 eV Solar modulation blocks low energy CRs 10 21 eV 10 9 eV Hillas_Rev_CRs_JPhysG2005.pdf Galactic Cosmic Rays 10 -28 10 4

2. Don Ellison, NCSU Consider efficient production of Cosmic Rays by Diffusive Shock Acceleration (DSA) in SNRs DSA is also called the first-order Fermi mechanism Many 100’s of references. Some review papers: Axford 1981; Drury 1983; Blandford & Eichler 1987; Jones & Ellison 1991; Berezhko & Ellison 1999; Malkov & Drury 2001; Bykov 2004; Bykov et al 2011, 2012, 2013 Discovery papers for first-order Fermi mechanism in shocks: Krymskii (1976), Axford, Leer & Skadron (1977), Bell (1978), Blandford & Ostriker (1978)  Particle acceleration in Collisionless Shocks  So called “Universal” test-particle power law for particles (in a strong shock) If particles are fully relativistic:

3. Contact Discontinuity Forward Shock Reverse Shock 1-D: Model Type Ia or core-collapse SN with Pre-SN wind Spherically symmetric: No clumpy structure for now (Note Yamazaki’s talk)

4. Contact Discontinuity Forward Shock Reverse Shock Shocked ISM material : Weak X-ray lines; Strong DSA and CR prod. 1-D: Model Type Ia or core-collapse SN with Pre-SN wind Spherically symmetric: No clumpy structure for now (Note Yamazaki’s talk)

5. Contact Discontinuity Forward Shock Reverse Shock Shocked Ejecta material : Strong X-ray emission lines ! DSA not obvious for RS unless B-field strongly amplified Shocked ISM material : Weak X-ray lines; Strong DSA and CR prod. 1-D: Model Type Ia or core-collapse SN with Pre-SN wind Spherically symmetric: No clumpy structure for now (Note Yamazaki’s talk)

6. Contact Discontinuity Forward Shock Reverse Shock Shocked ISM material : Weak X-ray lines; Strong DSA and CR prod. 1-D: Model Type Ia or core-collapse SN with Pre-SN wind Escaping CRs 1)Cosmic Ray electrons and ions accelerated at FS a)Protons  pion-decay  -rays b)Electrons  synchrotron, IC, & non-thermal brems. c)High-energy CRs escape from shock precursor & interact with external mass 2)Evolution of shock-heated plasma between FS and contact discontinuity (CD) a)Electron temperature, density, charge states of heavy elements, and X-ray line emission varies with ionization age Shocked Ejecta material : Strong X-ray emission lines ! DSA not obvious for RS unless B-field strongly amplified Spherically symmetric: No clumpy structure for now (Note Yamazaki’s talk)

7. Don Ellison, NCSU Main effects from DSA that influence SNR hydrodynamics : 1)Nonthermal particles (i.e., swept-up ISM or ejecta) are turned into relativistic CRs by DSA. This lowers specific heat ratio (5/3  4/3) 2)Some of the highest energy CRs will escape upstream from the forward shock. This also lowers specific heat ratio (4/3  1)  Effects (1) and (2) cause the shock compression ratio to increase above r = 4 (find typical values with efficient DSA : r ~ 5 - 10 ) 3) If DSA is efficient, to conserve energy, temperature of shocked gas MUST decrease below value expected without CR production SNR shocks that efficiently produce CRs will have large compression ratios and low shocked temperatures  Production of CRs influences SNR hydrodynamics & thermal X-ray emission

8. ►For strong shocks, “universal power law” diverges unless acceleration stopped by finite size or finite age. Diverges for strong shocks with compression ratio r  4 “Universal” power law diverges for r = 4  In strong shocks, CRs must modify the shock, and some of the highest energy CRs must escape if acceleration is efficient  strong nonlinear effects Test-particle power law hardens with increasing comp. ratio, r

9. What happens to the test-particle prediction when nonlinear effects are taken into account? First: Collisionless plasmas :

10. NGC 2736: The Pencil Nebula Hydrogen emission SN 1006 Thin structures are possible because wave-particle interactions produce short mfp for particle isotropization Collisionless plasmas :  We see “thin” structures in solar wind and ISM : e.g., planetary bow shocks and SNR shocks  The length scale of these structures must be many orders of magnitude smaller than the collisional mean-free-path

11. Uniform B Charged particle, helix, no “  B/B scattering” Particle-particle collisions are rare

12. Uniform B Charged particle, helix, no “  B/B scattering” Particle-particle collisions are rare Turbulent B If particle flux large enough, particles will distort the field :

13. Uniform B Charged particle, helix, no “  B/B scattering” Particle-particle collisions are rare Turbulent B Particles pitch-angle scatter and turn around  can define a collisionless mean free path. This “collision” is nearly elastic in frame of B-field If particle flux large enough, particles will distort the field :

14. In collision-dominated plasmas, particle-particle collisions drive the plasma to thermal equilibrium. If an individual particle gets more energy than average, it will immediately transfer energy via collisions to slower particles  scatterings are Inelastic I n a collisionless plasma, particles interact with the background B-field  one proton “scatters” off of ~ Avogadro’s number of particles tied together by nearly “frozen-in” turbulent B-field  scatterings are nearly elastic An individual particle can gain, and keep for long times, much more energy than an average thermal particle B-fields are frozen-in because of high conductivity of diffuse plasmas. If the plasma moves, currents are generated to produce B-fields so magnetic flux remains unchanged. B-field moves with bulk plasma

15. 10 20 eV Energy [eV] Flux 10 15 eV Solar modulation blocks low energy CRs 10 21 eV 10 9 eV Hillas_Rev_CRs_JPhysG2005.pdf Galactic Cosmic Rays  Extremely non-equilibrium plasma maintained for many millions of years in ISM. Do not see this in laboratory plasmas !! LHC Need vast machines to produce high energy beam for a brief instant  Do not have diffusive shock acceleration in collision dominated (i.e., lab) shocks 

16. Diffusive Shock Acceleration: Shocks set up converging flows of ionized plasma Shock wave V sk = u 0 V DS Interstellar medium (ISM), cool with speed V ISM ~ 0 Post-shock gas  Hot, compressed, dragged along with speed V DS < V sk SN explosion

17. Diffusive Shock Acceleration: Shocks set up converging flows of ionized plasma Shock wave V sk = u 0 V DS Interstellar medium (ISM), cool with speed V ISM ~ 0 Post-shock gas  Hot, compressed, dragged along with speed V DS < V sk X flow speed, u 0 shock u2u2 Upstream DS charged particle moving through turbulent B-field Particles make nearly elastic collisions with background plasma  gain energy when cross shock  bulk kinetic energy of converging flows put into individual particle energy  some small fraction of thermal particles turned into (approximate) power law shock frame u 2 = V sk - V DS SN explosion

18. Plot p 4 f(p) Normalization of power law not defined in test-particle approximation Test Particle Power Law Krymsky 77, Axford at al 77, Bell 78, Blandford & Ostriker 78 f(p) ~ p -3r/(r-1) where r is compression ratio, f(p) d 3 p is phase space density If r = 4, &  = 5/3, f(p) ~ p -4 X flow speed shock Quasi-Universal power law p 4 f(p)

19. Plot p 4 f(p) Normalization of power law not defined in test-particle approximation Test Particle Power Law Krymsky 77, Axford at al 77, Bell 78, Blandford & Ostriker 78 f(p) ~ p -3r/(r-1) where r is compression ratio, f(p) d 3 p is phase space density If r = 4, &  = 5/3, f(p) ~ p -4 X flow speed shock Test particle results: ONLY for superthermal particles, no information on thermal particles Quasi-Universal power law p 4 f(p)

20. X subshock Flow speed ► Concave spectrum ► Compression ratio, r tot > 4 ► Low shocked temp. r sub < 4 Temperature TP: f(p)  p -4 test particle shock NL If acceleration is efficient, shock becomes smooth from backpressure of CRs In efficient acceleration, entire particle spectrum must be described consistently, including escaping particles  much harder mathematically BUT, connects thermal emission to radio & GeV-TeV emission p 4 f(p) [f(p) is phase space distr.] p 4 f(p) B-field effects may reduce curvature

21. X subshock Flow speed test particle shock Efficient acceleration  shock becomes smooth from CR backpressure Weak subshock, r < 4  lower shocked temperature Overall compression ratio > 4  higher shocked density Temperature and density determine non-equilibrium ionization state of shocked plasma  SNR evolution & X-ray emission modified by efficient shock acceleration  Caution: while basic predictions are extremely robust – They only depend on particle diffusion length being increasing function of energy,  Size of nonlinear effects depend on acceleration efficiency.

22.  Efficient DSA  Test-particle accel. Comp. ratio Shocked proton temp. Modifications brought on by efficient CR production depend on Mach number (here show extreme example) TP NL TP Increase in compression ratio and Decrease in shocked temperature with efficient CR acceleration These are large effects when B ISM is low. Not so large if B-field amplifed 4 Compression ratios >> 4 should show in SNR morphology 20 10 SNR Age [yr]

23. Green line is contact discontinuity (CD) CD lies close to outer blast wave determined from 4-6 keV (non-thermal) X-rays Chandra observations of Tycho’s SNR (Warren et al. 2005) 2-D Hydro simulation Blondin & Ellison 2001 No acceleration Efficient DSA acceleration FS Morphology can be explained by large compression ratio from efficient DSA

24. X subshock Flow speed test particle shock Efficient acceleration  shock becomes smooth from CR backpressure High momentum CRs feel larger effective compression than low p CRs  Smooth shock produces concave spectrum Note: plot p 4 f(p) High efficiency example Particle spectrum that determines highest energy emission is fundamentally connected to lowest energy thermal plasma

25. synch IC brems pion Particle distributions continuum emission p’s e’s In addition, emission lines in thermal X-rays. Depends on T e /T p and electron equilibration model In nonlinear DSA, Thermal & Non-thermal emission coupled  big help in constraining parameters Several parameters needed for modeling !! e.g., Electron/proton ratio, K ep K ep

26. Have developed a Composite SNR Model (CR-hydro-NEI code) SNR hydrodynamics, Nonlinear Shock Acceleration, Broadband continuum radiation, and X-ray emission line Collaborators: Andrei Bykov, Daniel Castro, Herman Lee, Hiro Nagataki, Dan Patnaude, & Pat Slane (early work with: Anne Decourchelle & Jean Ballet 2000,2004) 1)VH-1 code for 1-D hydrodynamics of evolving SNR (e.g., J. Blondin) 2)Semi-analytic, nonlinear DSA model (from P. Blasi and co-workers) 3)Non-equilibrium ionization for X-ray line emission (D. Patnaude, J. Raymond) 4)NL shock acceleration coupled to SNR hydrodynamics (Herman Lee) 5)Magnetic field amplification (Blasi’s group & Andrei Bykov) 6)Electron and Ion distributions from thermal to relativistic energies (T. Kamae) 7)Continuum photon emission from radio to TeV 8)Simple model of escaping CRs propagating beyond SNR Apply model to individual SNRs: RX J1713, CTB 109, Vela Jr., Tycho

27. p-p IC brems Core-collapse SN model SN explodes in a 1/r 2 pre-SN wind  Shell of swept-up wind material  Inverse-Compton dominates GeV-TeV emission Note good fit to highest energy HESS observations Inverse-Compton fit to HESS obs: Pre-SN wind B-field lower than ISM  Can have MFA and still have B-field low enough to have high electron energy. For J1713, we predict average shocked B ~ 10 µG ! Note: Large majority of CR energy is still in ions even with IC dominating the radiation  SNRs produce CR ions! synch One example: Thermal & Non-thermal Emission in SNR RX J1713 (Ellison, Lee, Slane, Patnaude, Nagataki et al 2007--2012)

28. High densities needed for pion-decay may be in cold clumps that don’t radiate thermal X-ray emission Inoue et al (2012) Multi-component model for SNR RX J1713 (Inoue, Yamazaki et al 2012; Fukui et al 2012): Average density of ISM protons: ~130 cm -3 Total mass ~2 10 4 M sun over SNR radius ~0.1% of supernova explosion energy in CR protons !! This may be a problem for CR origin

29. Warning: many parameters and uncertainties in CR-hydro-NEI model, but : For spherically symmetric model of SNR RX J1713 & Vela Jr.: Inverse-Compton is best explanation for GeV-TeV Other remnants can certainly be Hadronic or mixed, e.g. Tycho’s SNR and CTB 109. Important: For DSA most CR energy (~17% of E SN for J1713) is in ions even with inverse-Compton dominating the radiation  All nonlinear models show that SNRs produce CR ions !!!  There is no fundamental difference between IC and pp dominated SNRs Besides question of CR origin: Careful modeling of SNRs can provide constraints on critical parameters for shock acceleration: a)Shape and normalization of CR ions from particular SNRs b)electron/proton injection ratio c)Acceleration efficiency d)Magnetic Field Amplification e)Properties of escaping CRs f)Geometry effects in SNRs such as SN1006 What about CRs observed at Earth? CREAM Balloon flights

30. Float between ~38 and ~40 km Average atmospheric overburden of ~3.9 g/cm 2 Total exposure for 5 flights ~156 days CREAM Balloon flights in Antarctica 40 million cubic foot balloon

31. Figure from P. Boyle & D. Muller via Nakamura et a. 2010 Spectral shape of cosmic ray electron spectrum is similar to ions when radiation losses are considered. Cosmic rays measured at Earth Side note: Stochastic (second-order) acceleration cannot reproduce such similar spectral shapes. Stochastic acceleration is NOT acceleration mechanism for these galactic CRs

32. Don Ellison, NCSU Recent balloon and spacecraft observations of cosmic rays show “unexpected” spectral shapes, e.g.: ATIC-2 (Wefel et al. 2008); CREAM (Ahn et al 2010); PAMELA (Adriani et al. 2011) 1)Hint of curvature in CR spectra  this might be concave curvature predicted by nonlinear DSA !? 2)CR helium spectrum is slightly harder that the proton spectrum at energies where both are fully relativistic  This is impossible to explain with “simple” NL DSA. Must be more complicated. PAMELA (Adriani et al. 2011) p/He Rigidity (GV), R = pc/(eZ)

33. CREAM data from Ahn et al 2010 Protons (open) Helium (solid) iron O Si C He Different shape for H and He spectra & Hint of curvature in CR spectra seen at Earth !? Concave curvature? Ne Mg

34. Log Velocity Log f(v) (p.s.d.) Velocity Scale, v << c Test-particle power laws Electrons Protons High A/Q ions Test-particle: All have identical spectral shapes in velocity (if scale to number of particles accelerated) What does basic model of Nonlinear DSA predict ? Consider spectral curvature when have different ion species.  In test-particle acceleration, DSA predicts spectra ordered by velocity This results from assumption that scatterings are elastic in local frame  nature of “collisionless” plasma  Once all particles are fully relativistic they are treated the same Test-particle

35. Log Velocity Log Momentum protons electrons Log f(v) (p.s.d) electrons, proton high A/Q identical Velocity Scale, v << c Momentum scale Log f(p) (phase space) Test-particle power laws Heavy particles get more energy purely from the kinematics of energy gain in the converging plasmas on either side of the shock Test Particle Shock Acceleration High A/Q Test-particle power-law: same for all ion species

36. If shock is efficient, nonlinear effects are important and shock is smoothed: Small A/Q particles feel a smaller effective compression ratio, r eff, high A/Q ions feel a larger r eff than protons at same velocity High A/Q particles gain more energy in each crossing  have a flatter spectrum than protons until both are relativistic This effect depends on acceleration efficiency and on shock Mach number X Flow speed Test Particle Modified shock Modified shock  concave spectrum Note: plot p 4 f(p)

37. Log Momentum Momentum scale Non-linear effects X Flow speed Test Particle Modified shock electrons protons high A/Q ions e’s p A/Q Diffusion length proportional to A/Q means high A/Q species suffer LESS from modified shock If shock is modified mainly by protons, high A/Q ions will be enhanced, in acceleration process When nonlinear effects become important, momentum dependence of mfp gives CONCAVE spectra (Eichler 79, 84) e’s p A/Q enhancement depletion Log f(p) (phase space)

38. Bottom line: Nonlinear DSA predicts : Enhancement of high A/Q (mass/charge) particles. Heavy elements accelerated more efficiently than protons  Observed at quasi-parallel Earth bow shock  May explain difference in H/He slopes, but detailed modeling necessary  Essential for modeling the composition of Galactic Cosmic Rays High A/Q (mass / charge) ions gain more energy in each crossing and have a flatter spectrum than protons as long as they are non-relativistic. Enhancement then persists to relativistic energies X Flow speed Test Particle Modified shock

39. Ellison, Mobius & Paschmann 90 Quasi-parallel Earth Bow Shock AMPTE / IRM observations of diffuse ions at Q- parallel Earth bow shock H +, He 2+, & CNO 6+ Observed during time when solar wind magnetic field was nearly radial. Critical range for injection Data shows high A/Q solar wind ions injected and accelerated preferentially. These observations are consistent with A/Q enhancement in nonlinear DSA (Eichler 1979) DS UpS DS Modeling suggests nonlinear effects important H+H+ He 2+ CNO 6+

40. A/Q enhancement applied to Galactic Cosmic Ray Composition Observed CR composition NOT so similar to solar system !!! Lodders 2003 Scale to Silicon Li, Be, B produced by heavier CRs breaking up as collide in ISM Here, scale to Silicon Note composition measurements restricted to low energy CRs < 100 GeV

41. Scale to Hydrogen Galactic Cosmic Ray Composition Galactic abundances Li Be B Simpson 83 ► Main effect is enhancement of all heavy elements relative to Hydrogen & Helium (factor of ~10) ► Secondary effect is enhancement of refractory elements (Dust) relative to volatile ones (Gas) (factor of ~10) Consistent explanation of CR source material: Nonlinear SNR shocks accelerate ISM gas and dust with A/Q enhancement Meyer, Drury & Ellison 1997

42. Ni Fe Ca Al Si Ti Silicon Iron Calcium 100% in gas phase >99% in dust Meyer, Drury, & Ellison 97 Aluminum ISM gas-phase abundances Dust Those elements that are most abundant in CRs are locked in dust in ISM ! You must accelerate ISM dust to reproduce observed (low energy) CR composition

43. Ellison, Drury & Meyer 1997 Elements that are locked in dust in ISM Gaseous elements H He CR source/solar Mass, A ~ (A/Q) Scale to Hydrogen 10 100 1 1 10 A/Q enhancement of ISM gas and dust accelerated by SNR shock. Dust sputters off refractory ions which are then re-accelerated by shock Large error bars here, but more recent observations by TIGER and ACE are much better 

44. Figure (preliminary) from M. Israel (Denver CR meeting, June 2012) Refractories (Dust) Volatiles (Gas) New data from TIGER and ACE. M. Israel et al. compare with 80% mixed ISM and 20% massive star outflow & ejecta. Support for Gas-Dust model. Clear evidence for A/Q enhancement of both Volatiles & Refractories H and He are not on this plot. Until Meyer et al 1997, H and He were treated as “exceptions” and not included with heavy elements. H and He did not fit FIP scenario. Note: Mass, A ~ (A/Q)

45. Particle acceleration requires magnetic turbulence to work. This turbulence must be far stronger than typical ISM  B/B to produce CRs to high energy Shocks can, and do, produce their own turbulence. No independent, external source of turbulence is necessary for DSA to take place. When a supersonic plasma, even one with zero B-field, encounters a barrier :  currents will be generated by particles reflecting off barrier,  small-scale B-fields result (call this the Weibel instability if you like),  fresh, unshocked particles now gyrate in these fields and become randomized,  a shock quickly forms,  particles start to be accelerated by the shock and the streaming instability generates more magnetic field, etc…. Magnetic Field Amplification (MFA):

46. Baring et al ApJ 1997 Self-generated turbulence at weak Interplanetary shock  B/B Indirect evidence for strong turbulence produced by CRs at strong SNR shocks Tycho’s SNR Sharp X-ray synch edges

47. Bell & Lucek 2001  apply Q-linear theory when  B/B >> 1; Bell 2004  non-resonant streaming instabilities Amato & Blasi 2006; Blasi, Amato & Caprioli 2006; Vladimirov, Ellison & Bykov 2006, 2008 How do you start with B ISM  3  G and end up with B  300  G at the shock? Efficient diffusive shock acceleration (DSA) not only places a large fraction of shock energy into relativistic particles, but also amplifies magnetic field by large factors MFA is connected to efficient CR production, so nonlinear effects essential } calculations coupled to nonlinear particle accel.

48. A lot of work by many people on nonlinear Diffusive Shock Acceleration (DSA) and Magnetic Field Amplification (MFA) Some current work (in no particular order): 1)Amato, Blasi, Caprioli, Morlino, Vietri: Semi-analytic 2)Bell: Semi-analytic and PIC simulations 3)Berezhko, Volk, Ksenofontov: Semi-analytic 4)Malkov: Semi-analytic 5)Niemiec & Pohl: PIC 6)Pelletier and co-workers: MHD, relativistic shocks 7)Reville, Kirk & co-workers: MHD, PIC 8)Spitkovsky and co-workers; Hoshino and co-workers; other PIC simulators: Particle-In-Cell simulations, so far, mainly rel. shocks 9)Caprioli & Spitkovsky; Giacalone et al.: hybrid simulations 10)Vladimirov, Ellison, Bykov: Monte Carlo 11)Zirakashvili & Ptuskin: Semi-analytic, MHD 12)Bykov et al 13)Apologies to people I missed …

49. 1)Magnetic field generation intrinsic part of particle acceleration  cannot treat DSA and MFA separately 2)Strong turbulence means Quasi-Linear Theory (QLT) not good approximation  But QLT is our main analytic tool (QLT assumes  B/B << 1) 3)Length and momentum scales are currently well beyond reach of 3D particle-in-cell (PIC) simulations if wish to see full nonlinear effects  Particularly true for non-relativistic shocks a)Problem difficult because TeV protons influence injection of keV protons and electrons 4)To cover full dynamic range, must use approximate methods: e.g., Monte Carlo, Semi-analytic, MHD simulations Magnetic Field Amplification in DSA is a hard problem

50. Thermal leakage Injection Acceleration Efficiency magnetic turbulence,  B/B  diffusion coefficient dissipation, & cascading Shock structure If acceleration is efficient, all elements feedback on all others Using approximate plasma physics (quasi-linear theory, Bohm diffusion, etc.) Can iteratively solve nonlinear DSA problem with MFA (Monte Carlo work with Andrei Bykov, Andrey Vladimirov & Sergei Osipov) iterate Iterative, Monte Carlo model of Nonlinear Diffusive Shock Acceleration (i.e., Vladimirov, Ellison & Bykov 2006,2008; Ellison & Vladimirov 2008) Similar semi-analytic results: Amato & Blasi (2006); Blasi, Amato & Caprioli (2006) Work with Bykov, Osipov & Vladimirov

51. Essential features of MFA in diffusive shock acceleration: 1) Production of turbulence, W(x,k) (assuming quasi-linear theory) a)Resonant (CR streaming instability) (e.g., Skilling 75; McKenzie & Volk 82; Amato & Blasi 2006) b)Non-resonant current instabilities (e.g., Bell 2004; Bykov et al. 2009; Reville et al 2007; Malkov & Diamond) i.CR current produces waves with scales short compared to CR gyro-radius ii.CR current produces waves with scales long compared to CR gyro-radius 2) Calculation of D(x,p) once turbulence is known a)Resonant (QLT): Particles with gyro-radius ~ waves gives part ∝ p b)Non-resonant: Particles with gyro-radius >> waves gives part ∝ p σ 3) Production of turbulence and diffusion must be coupled to NL shock structure including injection of lowest energy particles and escape of highest energy All coupled  (1) Thermal injection; (2) shock structure modified by back reaction of accelerated particles; (3) turbulence generation; (4) diffusion in self-generated turbulence; (5) escape of maximum energy particles  All coupled

52. Conclusions: 1)The production of CRs in young SNRs is expected to be efficient and nonlinear: theory and observations support this in individual remnants 2)DSA is intrinsically efficient and difficult !  Shock structure, CR production, B-field turbulence, Injection of thermal particles, all non-trivially connected 3)DSA is multi-scale (Intrinsic concave CR spectrum)  Large fraction of total energy is in highest energy CRs with longest diffusion lengths  To conserve energy, highest energy CRs must feedback on injection of lowest energy particles with shortest diffusion lengths 4)Injection of thermal particles, escape of high energy CRs, and self-generation of turbulence, all involve highly anisotropic distributions  Quasi-linear theory not good approximation 5)Detailed plasma physics important for nonlinear effects, but :  Multi-scale nature currently beyond reach of PIC simulations 6)Need to know how NL DSA works to explain origin of CRs and to properly interpret broadband SNR observations (also radio jets, GRBs …. )  NL DSA influences the evolution and morphology of SNRs and the thermal X-ray emission

53. Extra Slides

54. PAMELA (Adriani et al. 2011) protons Helium Confirm different slopes: Helium harder than protons at fully relativistic energies !  This is impossible to explain with “simple” NL DSA. Must be more complicated. ATIC-2 (Wefel et al. 2008)

55. Don Ellison (NCSU) Talk at UNC March 2006 FS CD Reverse shock Radius (arcsec) Radius / FS Azimuthal angle (deg) CD Chandra observations of Tycho’s SNR (Warren et al. 2005) After Warren et al. adjust for distortions at the CD: Observed

56. Don Warren & John Blondin 2013 3D hydro simulations showing positions of forward shock, reverse shock and contact discontinuity. Includes a phenomenological model of NL DSA  Efficient DSA causes CD-FS separation to decrease  Rayleigh-Taylor instabilities alone can allow ejecta knots to move ahead of FS No DSA Efficient DSA RS-CD-FS positions If you want clumpy:

57. Don Warren & John Blondin 2013 Knots of ejecta material have overtaken forward shock ejecta knot No DSA medium eff. efficient DSA Tycho Line-of-sight simulation of thermal X-ray and non-thermal synchrotron emission (crude model for synch.) Compared to Chandra X-ray obs. of Tycho’s SNR (J.Warren et al. 2005) For now, stay with 1-D spherically symmetric model with good NL DSA calculation

58. 3D hydro simulation with X-ray lines and efficient DSA (Ferrand et al. 2012) Thermal emission (0.3 – 10 keV) from shocked ISM and ejecta material Includes effects from back reaction of CRs on thermal plasma Hydro simulations are important steps forward but not so easy to include NL-DSA in 3D models No CR back- reaction With CR back-reaction