Core Collapse Supernovae An Emerging Picture Stephen W. Bruenn

Transcription

1 Core Collapse Supernovae An Emerging Picture Stephen W. Bruenn 19th Rencontres de Blois Matter and Energy in the Universe: from nucleosynthesis to cosmology

2 Collaborators Anthony Mezzacappa John M. Blondin John C. Hayes Oak Ridge National Lab North Carolina State UC at San Diego W. Raph Hix Oak Ridge National Lab O. E. Bronson Messer Oak Ridge National Lab 19th Rencontres de Blois Matter and Energy in the Universe: from nucleosynthesis to cosmology

3 Core Collapse Supernova Energetics Photons ~ ergs Ejecta Kinetic energy ~ ergs Neutrinos ~ 3x10 53 ergs 19th Rencontres de Blois Matter and Energy in the Universe: from nucleosynthesis to cosmology

4 Core Collapse Supernova Polarization Asymmetries Core collapse SN are polarized at ~1% level Degree of polarization increases with decreasing envelope mass Degree of polarization generally increases after optical maximum Outward mixing of Ni in SN1987 A & Cas A Axisymmetric ejecta of SN1987A Early Emission of x-rays and γ-rays from SN1987A Pulsar kicks 19th Rencontres de Blois Matter and Energy in the Universe: from nucleosynthesis to cosmology

5 Direct Imaging SN 1987A Suggests a Bipolar Structure SN 1987A November 28, 2003

6 Supernova Connections Neutron Stars Nucleosynthesis Supernovae Neutrino Signatures Black Holes Gravitational Waves

7 Core Collapse Supernova Scenario neutrinos shock

8 Aftermath neutrinos photons matter neutron star or black hole

9 The Supernova Problem Matter Flow Neutrino flow Shock _ ν e + n p + e - ν e + p n + e + _ ν e + n p + e - ν e + p n + e + Protoneutron Star Gain Radius ν-spheres Cooling Heating

10 The Core Collapse Supernova Mechanism: A Computational Challenge Inherently multi-dimensional Variety of complex physical processes that need to be accurately modeled Explosions are marginal 19th Rencontres de Blois Matter and Energy in the Universe: from nucleosynthesis to cosmology

11 Supernova Code Hydrodynamics Nuclear Reactions Neutrino Transport

12 Hydrodynamics Lagrangian PPM with Remap implementation of a Godunov scheme Newtonian spectral Poisson solver with effective GR radial potential Spherical polar grid Moving radial grid option during infall, adaptive below shock after shock generation 19th Rencontres de Blois Matter and Energy in the Universe: from nucleosynthesis to cosmology

13 Hydrodynamics Implementation e i + e k + e g in shock if! < g cm -3, e i + e k in shock if! > g cm -3, e i elsewere evolve e i + e k + e g, remap e i + e k e i + e k in shock, e i elsewere e i + e k + e g everywhere e i + e k everywhere 11.2 M O 1D. Improved Opacities evolve e i + e k, remap e i + e k + e g e i + e k + e g if! < g cm -3, e i + e k if! > in shock, e i outside of shock if! > t post bounce (s)

14 Nuclear Network 4 He, 12 C, 16 O, 20 Ne, 24 Mg, 28 Si, 32 S, 36 Ar, 40 Ca, 44 Ti, 48 Cr, 52 Fe, 56 Ni, 60 Zn n, p, Fe-like tracers Advection of material into and out of NSE Flashing and freeze-out of zones 19th Rencontres de Blois Matter and Energy in the Universe: from nucleosynthesis to cosmology

15 Neutrino Transport Multigroup, flux-limited diffusion tuned to Boltzmann transport Ray-by-ray plus approximation Full flavor implicit solve All O(v/c) velocity corrections, red shift and time dilation effects included 19th Rencontres de Blois Matter and Energy in the Universe: from nucleosynthesis to cosmology

16 Neutrino Interactions Emission and Absorption of ν e s e + p, A(Z, N) ν e + p, A(Z 1, N + 1) Emission and Absorption of ν e s e + + n, A(Z, N) ν e + p, A(Z + 1, N 1) Neutrino-Electron, Neutrino-Positron Scattering ν e,µ,τ, ν e,µ,τ + e, e + ν e,µ,τ, ν e,µ,τ + e, e + Neutrino Scattering on Nucleons and Nuclei ν e,µ,τ, ν e,µ,τ + n, p, A ν e,µ,τ, ν e,µ,τ + n, p, A Electron-Positron Pair Annihilation e + e + ν e,µ,τ + ν e,µ,τ Nucleon-Nucleon Bremsstrahlung N + N N + N + ν e,µ,τ + ν e,µ,τ Neutrino-Neutrino Scattering ν e,µ,τ + ν e,µ,τ ν e,µ,τ + ν e,µ,τ

17 Progenitor Structure M Ȯ 15.0 M Ȯ M Ȯ Mass Enclosed (M O ).

18 S15s7b 15 ms post bounce

19 S15s7b 100 ms post bounce

20 S15s7b 200 ms post bounce

21 S15s7b 621 ms post bounce

22 20M 256x256 O.

23 2D Supernova Simulations Stellar Mass Gravity Opacities Resolution 20 Groups t (ms pb) Explosion Energy (B) Remnant (M O ). 11 (S11s7b) N Standard 192 X Y (S11s7b) N Standard 192 X Y (S11.2) N Improved 256 X Y (S11.2) GR Improved 256 X Y (S11.2) N Improved 256 X Y (S11.2) GR Standard 256 X Y (S11.2) GR Improved 256 X Y (S15s7b) N Standard 192 X Y (S15) N Improved 256 X (S15) GR Improved 256 X (S20) N Improved 256 X Possibly 20 (S20) GR Improved 256 X Possibly

24 Why Are We Getting Explosion? Convection driven by neutrino heating Improved neutrino rates Energy deposition by nuclear reactions SASI (Standing Accretion Shock Instability) 19th Rencontres de Blois Matter and Energy in the Universe: from nucleosynthesis to cosmology

25

26 SASI

27 Neutrinospheres Neutrinospheres Heating Cooling Protoneutron Star! e s _! e s _! µ s,_! µ s,! " s,! " s,! e -sphere _! e -sphere! µ & " -sphere

28 1D Supernova Simulations 150 S11.2, 63 ms post bounce shock em - ab! - e -,e + scat! +! - e - + e +! + N scat N + N brem Net 1x10 7 1x10 8 1x10 9 1x x x10 12 " (g cm -3 )

29 1D Supernova Simulations Neutrino Luminosities M O GR 1D. Stand opacities Stand + Brem opacities Stand + (! + N) opacities Stand + Brem + (! + N) opacities t post bounce (s)

30 Conclusions 2D simulations with spectral neutrino transport exhibit explosions for the 11.2 and 20M models, and probably for the 15M model as well. The simulations must be continued for longer times to ascertain the explosion energies of the models.

31 Future Work Investigate the observables of the exploding models---nucleosynthesis, neutrino and gravitational wave signatures, neutron star masses and kick velocities. Move to 3-D Use a singularity-free grid Incorporate magnetic fields