2014/7/8 Joint Meeting among RESCEU-RIKEN-IPMU＠RIKEN

Explosion Mechanism ofCore-collapse Supernovae
Tomoya Takiwaki(NAOJ->RIKEN)

Press Release in April

There are two press release on supernovae in last April
One: Lensed extremely luminous type Ia supernova.
The other: 3D explosion of type II supernova found in Kcomputer.

Why is CC SN interesting?
 Last time of massive stars
 Birth of neutron star Mother of supernova remnant

 One of the most luminous object in the universe
 Target of Multi-messenger astrophysics
 Source of heavy elements in galaxies
 4 kinds of force affects the explosion mechanism

Ni mass~ E_exp

Various Kinds of CC supernovae

Nomoto+2006

Initial Mass of Progenitor

Fate of the stardiffers from theproperties of theprogenitor:
1. Mass
2. Metallicity
3. Rotation
4. Magnetic Field

Two class of CC SNe
We focus on thisNeutrino Mechanism

Magnetic Mechanism

Rotation

Magnetic Fields
Rotation

BH

magnetarpulsar
MassMassNeutrino Mechanism
I’ll explain one by one

1. Initial setup
2. Key aspects of neutrino mechanism
3. Simulations4. Effect of Rotation

Neutrino Mechanism
I’ll explain one by one

1. Initial setup
2. Key aspects of neutrino mechanism
3. Simulations
4. Effect of Rotation

Key aspects of Neutrino Mechanism
Radial Velocity
Post ShockPostshockedn,pPressure

Shock

The shock is stalling.
Pressure inside and ram
Preshocked pressure out side balances.

FeRam Pressure

RHS is determined by stellar
structure(density profile).
RadiusEntropy~T^3/ρ

Fe=>n, pProto
NeutronStar

Heated by cooled byneutrino photodissociation

LHS is determined by twoingredients.
(1) Photodissociation(2) Neutrino HeatingA example of the failed supernovae
Non-Explosion
Is observed

Entropy isvisualized
Spherical
symmetricsimulations

Key aspects of Neutrino Mechanism
Entropy~T^3/ρ
Heated byconvection

Fe=>n, pProto
NeutronStar

Heated byneutrinocooled byphotodissociation

Negative entropy gradientleads Rayleigh-Taylor
instability(Cold heavy matter is put over
Hot light matter)
Rayleigh-Taylor convection
transfer energy outward.

RadiusCooler than
the initialstate but νheat is active

Hotter than
the initialstateNeutrino Mechanism
I’ll explain one by one

1. Initial setup
2. Key aspects of neutrino mechanism
3. Simulations
4. Effect of Rotation

s11.2(Light Progenitor) Ω=0rad/s
Explode!
Convection
Dominant
EoS：LS-K220

resolution：
384(r)x128(θ)x256(φ)
The finest grid
Neutrino Trasport：
Ray-by-Ray:IDSA+Leakage
Hydro:
HLLE, 2nd orderShape of the explosion？
Many hotbubble isobserved.
That isevidence ofstrong
convection.

s27(heavey Progenitor) Ω=0rad/s
Failed(or need long-term sim.)

EoS：LS-K220

resolution：
384(r)x64(θ)x128(φ)

Neutrino Transport：
Ray-by-Ray:IDSA+Leakage

Hydro:
HLLE, 2nd orderNeutrino Luminosity

Mass accretion vs neutrino heating
explodeGR effect?

11.2

Heavier progenitor
results high massaccretion rate andhigh ram pressure.
That spoils theexplosion.

27.0
fail

Mass accretion rate

GR effects(orupdate ofmicrophysics) canchange thesituation.

Nakamura+14.

Nakamura+ 14.

slide from suwa

Nakamura+ 14.

Nakamura+ 14

Neutrino Mechanism
I’ll explain one by one

1. Initial setup
2. Key aspects of neutrino mechanism
3. Simulations
4. Effect of Rotation

Bar mode instability
Rapid Rotation => spiral instability

In the rigid ball,
Rotational energy(T)/gravtational energy(W)=14%
In Sne case, criteria becomes smaller.
Called low-T/W instability

Neutrino + rotation

Spiral wave transfer the energy to the outer regon.
Finally explosion is found!

Shape of the explosion？
Strongexpansion
is found atequatorialplane

The mass of the progenitor and rotation make various type ofExplosion(or Non Explosion).

Does rotation affect the shock revival?
Rapid rotations１１．２

s27.0
Rapid rotation

N１３

1D=> no shock revival
s11.2 : No
N13 : Yess27 : Yes

How energetic is that?
s１１．２
Rapid rotation

N１３

Rapid rotation

Observe 0.1-0.4 10^51erg!
It’s close to 10^51 erg!

s27.0
Rapid rotation

Message
Although CC SNe are not completely
understood, we are close to solve the problem.
(It’s might be semi-final match or final match?)
Quite nice model (close to the real one) can beobtained.
When should we start the collaboration on
astronomy with realistic supernovae model?

Now’s the time!

超新星シミュレーションの新問題
多次元モデルは物理のインプットに敏感で手法によって爆発したりしなかったりする。
爆発する
２次元モデル（複数親星に対して）
Bruenn+12：全部爆発
Mueller+13：おおよそ爆発
Dolence+14：一つも爆発しない
Nakamura+14：全部爆発
2D 3D
Suwa in prep：半分ほど爆発
Hanke in prep：おおよそ爆発
インプットのエラーの範囲
３次元モデル（複数親星に対して）Hanke in prep：一つも爆発しない
1D
爆発しない
Takiwaki in prep：半分ほど爆発

超新星シミュレーションの新問題
多次元モデルは爆発するにせよしないにせよ非常にぎりぎり。

定量的な評価を確定する
ためには相当手法に凝る必要がある！

Ott+12

今後は数値計算の信頼性がとにかく大事！

ロードマップとにかくすべてのインプットをアップデートせよ！
Most realistic modelの変遷。

６次元ボルツマン

Kuroda in prep
Hanke+13

Takiwaki+14

フルＧＲ
Non Ray-by-Ray

ニュートリノ反応
現象論的ＧＲ

ペタスケールエクサスケール～２０２０

Kuroda論文での結論と６次元ボルツマンでの計算に今後は注目！
２０２０年ぐらいまでにはかなりの決着を見るのでは？

ニュートリノ＋磁場磁気回転不安定性で対流安定な場所でも乱流的になる。
それがニュートリノ加熱に効くかもしれない。

高解像度計算が必要
すぐに完全な計算はできない
徐々に調べる

現在、政田くんと研究中。澤井くんも同様のことを指摘。

ニュートリノ＋ＳＡＳＩ爆発
Advective-acoustic cycle

Foglizzo’s slides

Pressure Wave

Vorticity Wave

Standing Accretion Shock Instability(SASI)
渦が落ちる時間スケールで成長が律速。
上から物がどんどん降ってくるとき成長しやすい

Scheck+ 2008

ＳＡＳＩ爆発は起こるか？
２Ｄ

３Ｄ

Takiwaki+2012

Iwakami+14

ＣＣ的に爆発しにくいところでドミナントになる。この不安定性で爆発に転じるのは今のところ難しい見通し。