素核宇融合による計算基礎物理学の進展 2011/12/04＠合歓の郷

超新星爆発の３D シミュレーション
Takiwaki, T., Kotake, K., & Suwa, Y. 2011, submitted to ApJ; arXiv:1108.3989
and recent result

Tomoya Takiwaki
National AstronomicalObservatory of Japan
HPCI researcher

Supernovae
neutrino driven explosion
ν trapping

core collapse

core bounce

C+OHeHνSiFeν
νSN explosion

νν

ν

ν

shock propagation in coreshock in envelope

ν

NSν

ν
ν

ν

History of supernovae studies
 Baby Phase(Colgate &White ’66)
began simulation
importance of neutrino heating Young Phase (Wilson’82)
delayed explosion Adult Phase(e.g. Sumiyoshi et al. ’05)
1D spherical simulation could
not reproduce the supernovae
explosion.
Supernovae modelers devote
about 50 years to solve neutrinotransport with adequate accuracy.

Wilson 82

Sumiyoshi+ 05

Breakthrough by 2D simulations
Luminosity

Mass accretion rate

In 2D simulations, theneutrino luminosity
required for reviving shockis reduced !

Murphy & Burrows 2008

Is 3D simulation key for successful explosion?
Nordhaus et al. 2010

2D Cylindrical(Left) vs 3D Cartesian(Right) Gray Luminosity Adaptive mesh refinement is used

3D simulation require less luminosity compared to 2D!
Counter argument is presented by Hanke et al 2011. 3D model
might not be always good for explosion.
Under a realistic situation, is 3D good or bad?
Anyway… nature is 3D.

The feature of our study previous works

2D with spectral neutrino transport (Buras 2006, Marek &Janka
2009, Suwa et al. 2010) or
3D with simple assumption of neutrino luminosity (Iwakami et al
2008, Nordhaus et al. 2010)• this work
combining with good feature of
the previous work,
3D simulation with spectral
neutrino transport is presented!
Takiwaki, T., Kotake, K., & Suwa, Y. 2011,
submitted to ApJ; arXiv:1108.3989

Neutrino transport, concept

matter

Toward Thermal & Beta
equilibrium

Trapped neutrino
Diffusion
HeatingTransport

Neutrino sphere

IDSA( isotropic diffusion source approximations)
Dividing neutrino into two parts, trapped and free streamingFor ν_X, simple leakage scheme

Neutrino transport, trapped partf(x,y,z,E,theta,phi)
6 dimensional varable

Trapped Particle
Angular integration
Diffusion term
Energy integration

Determinedparameter for FermiDirac distribution
by Y and Z

Neutrino transport, free streaming partf(x,y,z,E,theta,phi)
6 dimensional varable

Weak coupling

Angular integration is performed.
Different from the original IDSA,
We treat the LHS explicitly and the RHS implicitly.
Newton Method is used for solving RHS.
No message passing during the iteration.

Result!
11.2M_s
LS EOS(K=180MeV)

Difference of Resolution

300x64x32

300x64x128

Fine structure inside the shock is producedin high-resolutional model!

Evolution of Shock

3D model is better than 2D model !

Advection time vs Heating time
Heating dominantCooling dominantProto neutron star

~60km
Advection time scale:
Accreted matter passes heating
dominant region in this time scale

Stalled shock~200km
Gain radius~100km

Heating time scaｌe:
The matter gain energy necessary
to unbound from gravitational
potential＞
If advection time scale is longer than heating time scale,explosion will succeed!

Neutrino Heating

3D model is better than
2D model !

Advection timescale(Sorry ! This slide is based on the previous work)

3D > 2D ! 3D is good for explosion(Same analysis should be done at the new work)

Summary
We perform first 3-dimensional simulation with spectral
neutrino transport.
 Advection time scale of 3D model is longer than thatof 2D. 3D is good for explosion.
 Neutrino luminosity of 3D model is bigger than 2Dwith same average energy.
As a result 3D is good for explosion in this resolution.
3D modeling of supernovae starts Young phase.
I wish this result (or tendency) is confirmed by models
with higher resolution, that is computed by K computer.

Simulation with K computer?
NAOJ-XT4
300x64x32
256 parallel

T2K-tukuba320x64x128
4096 parallel

K computer> 640x128x128> 16,384 parallel