2012/09/05

超新星放出ガス中でのダスト形成と衝撃波中でのダスト破壊野沢 貴也（Takaya Nozawa）
東京大学 国際高等研究所
カブリ数物連携宇宙研究機構（Kavli IPMU）

Collaborators;
T. Kozasa, A. Habe (Hokkaido University)
K. Maeda, K. Nomoto (IPMU), H. Umeda (U.T.)
N. Tominaga (Konan Univ.)

1. Introduction
・ supernovae (SNe) : explosions of massive (earlytype) stars with MZAMS > 8 Msun

・ SNe are important sources of interstellar dust?
－ huge amounts of dust grains (>108 Msun) are detectedin host galaxies of quasars at redshift z > 5➔ 0.1 Msun of dust per SN is needed to explain suchmassive dust at high-z (e.g. Dwek et al. 2007)－ contribution of dust mass from AGB stars and SNen(AGB stars) / n(SNe) ~ 10-20
Mdust = 0.01-0.05 Msun per AGB (Zhukovska & Gail 2008)
Mdust = 0.1-1.0 Msun per SN (Nozawa et al. 2003; 2007)

2. Dust Formation in Pop III SNe
at ~1 days
He-coreH-envelope

NS or BH
He–layer (C>O)
O–Ne-Mg layer
Dust formation
Si–S
atlayer~1-3 years
afterlayer
explosion
Fe–Ni2-1. Dust formation in primordial SNe
Nozawa+’03, ApJ, 598, 785〇 Population III SNe model (Umeda & Nomoto’02)
・ SNe II-P ： MZAMS = 13, 20, 25, 30 Msun (E51=1)
・ PISNe ： MZAMS = 170 Msun (E51=20), 200 Msun (E51=28)

Menv ~ 12 Msun

Menv ~ 90 Msun

・ nucleation and grain growth theory (Kozasa & Hasegawa’88)

・ complete and no mixing of elements within the He-core
・ complete formation of CO and SiO

2-2-1. Calculations of dust formation
・ nucleation and grain growth theory taking
account of chemical reaction at condensation(Kozasa & Hasegawa’87)

・ key species：
gas species with theleast collision frequency
among reactants

key species controls thekinetics of the nucleationand grain growth2-2-2. Nucleation rate of dust
Steady-state nucleation rate

Supersaturation ratio

2-2-3. Basic equations for dust formation
・ Equation of mass conservation

・ Equation of grain growth

Growth rate is independent of grain radius

2-3-1. Dust formed in primordial SNe
Nozawa+’03, ApJ, 598, 785

・ Various dust species (C, MgSiO3, Mg2SiO4, SiO2, Al2O3,MgO, Si, FeS, Fe) form in the unmixed ejecta, according
to the elemental composition of gas in each layer
・ The condensation time: 300-600 days for SNe II-P
400-800 days for PISNe

2-3-2. Size distribution of newly formed dust
Nozawa+’03, ApJ, 598, 785

・ C, SiO2, and Fe grains have lognormal size distribution,
while the other grains have power-law size distribution

・ The composition and size distribution of dust formed
are almost independent of type of supernova(average dust radius is smaller for PISNe than SNe II-P)

2-3-3. Size distribution of dust in mixed cases

・ Because oxygen is rich in the mixed ejecta, only
silicates (MgSiO3, Mg2SiO4, SiO2) and oxides (Fe3O4,Al2O3) form
・ The size distribution of each dust species except forAl2O3 is lognormal-like2-3-4. Total mass of dust formed
SNe II・ Total dust mass increases with increasing MZAMS
SNe II： Mdust = 0.1-2 Msun, fdep = Mdust / Mmetal = 0.2-0.3
PISNe： Mdust =10-60 Msun, fdep = Mdust / Mmetal = 0.3-0.5
・ Dust mass for the mixed case is generally larger thanfor the unmixed case

3. Dust Evolution in SNRs
T = (1-2)x104 K
nH,0 = 0.1-1 cm-3

He coreFSRSCD

3-1-1. Time evolution of SNRs

3-1-2. Initial condition for hydro calculations
・ Hydrodynamical model of SNe (Umeda & Nomoto’02)
・ SNe II : Mpr=13, 20, 25, 30 Msun (E51=1)
・ PISNe : Mpr=170 (E51=20), 200 Msun (E51=28)

・ The ambient medium (homogeneous)・ gas temperature : T = 104 K・ gas density : nH,0 = 0.1, 1, and 10 cm-3

・ Dust Model・ initial size distribution and spatial distribution of dust
➔ results of dust formation calculations
・ treating as a test particle
The calculation is performed from 10 yr up to ~106 yr

3-2-1. Dynamics of dust

3-2-2. Erosion rate of dust by sputtering3-2-3. Erosion rate of dust by sputtering
Nozawa+’06, ApJ, 648, 435
for primordial composition gas

for oxygen ions・ erosion rate by sputtering quickly increases above
105 K and peaks at 107 -108 K・ erosion rate : da / dt ~ 10-6 nH μm yr-1 cm3for the primordial gas (H and He) at T > 106 K

3-3-1. Temperature and density of gas in SNRs
Nozawa+’07, ApJ, 666, 955
Model : M pr= 20 Msun (E51=1)
nH,0 = 1 cm-3

Downward-pointing arrows:
forward shock in upper panel
reverse shock in lower panel
The temperature of the gas
swept up by the shocks➔ 106-108 K↓
Dust grains residing in theshocked hot gas are erodedby sputtering3-3-2. Evolution of dust in SNRs
Nozawa+’07, ApJ, 666, 955
Model : M pr= 20 Msun (E51=1)
nH,0 = 1 cm-3

Dust grains in the He core collidewith reverse shock at (3-13)x103 yr

The evolution of dust heavily
depends on the initial radiusand compositionaini = 0.01 μm (dotted lines)➔ completely destroyedaini = 0.1 μm (solid lines)➔ trapped in the shellaini = 1 μm (dashed lines)➔ injected into the ISM

3-3-3. Dust mass and size ejected from SN II-P
PISNe
SNe II-P

total dust mass surviving thedestruction in Type II-P SNRs;
0.07-0.8 Msun (nH,0 = 0.1-1 cm-3)

size distribution of dust after
RS destruction is domimatedby large grains (> 0.01 μm)

Nozawa+’07, ApJ, 666, 955
at time of dust formation

after destruction of dust
by reverse shock3-4. Summary of dust production in Pop III SNe
・ Various species of dust form in the unmixed ejecta(almost all Fe, Mg, and Si atoms are locked in dust)・ The fate of newly formed dust within primordial SNRs
strongly depends on the initial radii and compositions.

・ The size distribution of dust surviving the destructionin SNRs is weighted to relatively large size (> 0.01 μm).
・ The total mass of dust injected into the ISM decreaseswith increasing the ambient gas density
for nH,0 = 0.1-1 cm-3
SNe II-P ➔ Mdust = 0.1-0.8 Msun
PISNe ➔ Mdust = 0.1-15 Msun

3. Formation of dust grains invarious types of SNe

5-1. Dust formation in Type IIb SN○ SN IIb model (SN1993J-like model)－ Meje = 2.94 Msun
MZAMS = 18 Msun
MH-env = 0.08 Msun
－ E51 = 1－ M(56Ni) = 0.07 Msun

5-2. Dependence of dust radii on SN typeSN IIbSN II-P

0.01 μm－ condensation time of dust
300-700 d after explosion－ the radius of dust formedin H-stripped SNe is small－ total mass of dust formed
・ 0.167 Msun in SN IIb
・ 0.1-1 Msun in SN II-P・ SN IIb without massive
H-env ➔ adust < 0.01 μm

Nozawa+’10, ApJ, 713, 356

・ SN II-P with massive
H-env ➔ adust > 0.01 μm

5-3. Destruction of dust in Type IIb SNR
homogeneous CSM (ρ = const)

stellar-wind CSM (ρ ∝ r-2)
330 yrnH,1 = 30, 120, 200 /cc ➔ dM/dt = 2.0, 8.0, 13x10-5 Msun/yr for vw=10 km/s

Almost all newly formed grains are destroyed in shockedgas within the SNR for CSM gas density of nH > 0.1 /cc➔ small radius of newly formed dust
➔ early arrival of reverse shock at dust-forming region
Nozawa+’10, ApJ, 713, 356

5-4. IR emission from dust in Cas A SNRAKARI corrected 90 μm image

・ total mass of dust formed
Mdust = 0.167 Msun・ shocked dust : 0.095 Msun
Md,warm = 0.008 Msun
・ unshocked dust :Md,cool = 0.072 Msun
with Tdust ~ 40 K
Nozawa et al. 2010, ApJ, 713, 356

AKARI observation
Md,cool = 0.03-0.06 Msun
Tdust = 33-41 K(Sibthorpe+’10)

Herschel observation
Md,cool = 0.075 Msun
Tdust ~ 35 K (Barlow+’10)

6. Summary of this talk・ SNe are important sources of dust?
－ maybe, Yes in the early universe(at least, to serve the seeds for grain growth in the ISM)・ Size of newly formed dust depends on types of Sne－ H-retaining SNe (Type II-P) : aave > 0.01 μm－ H-stripped SNe (Type IIb/Ib/Ic and Ia) : aave < 0.01 μm➔ dust is almost completely destroyed in the SNRs
➔ H-stripped SNe may be poor producers of dust
・ Our model treating dust formation and evolution selfconsistently can reproduce IR emission from Cas A

・ Mass of dust in SNe must be dominated by cool dust
➔ FIR and submm observations of SNe are essential