2012/11/27

超新星爆発時におけるダストの凝縮・放出過程
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 (K-IPMU), H. Umeda (U.T.)
N. Tominaga (Konan Univ.)

1-1. Introduction
・ SNe are important sources of interstellar dust?
・ abundant metal (metal : N > 5)・ low temperature (T < ~2000 K)・ high density (n > ~106 cm-3)

mass-loss windsof AGB stars
expanding ejecta
of supernovae－ 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)

1-2. Summary of observed dust mass in CCSNe
SN1987A
Crabtheory
Cas A
missing cold dust?

young SNRs

swept-up IS dust?
young SNeby courtesy of M. Tanaka

Far-IR to sub-mm observations are essential for revealing
the mass of dust grains produced in the ejecta of SNe

1-2. Summary of observed dust mass in CCSNe
SN1987A
Crabtheory
Cas A
missing cold dust?

young SNRs

swept-up IS dust?
young SNeby courtesy of M. Tanaka

Far-IR to sub-mm observations are essential for revealing
the mass of dust grains produced in the ejecta of SNe

2. Dust Formation in the ejecta of SNe
at ~1 days
He-coreH-envelope

NS or BH
He–layer (C>O)
O–Ne-Mg layer
Dust formation
Si–Satlayer~1-3 years
afterlayer
explosion
Fe–Ni2-1. Concept of nucleation theoryc1c(2)J2c(3)

J3

αn-1c1cn-1 c(n)Jnβncn・ master equations

sn = 12-2. Steady-state nucleation rate
・ steady-state nucleation rate: Js

Js = J1 = J2 = ・・・ = Jn
= { 1/(α1c1) + ∑ 1/(αnc12) exp[g(n)] }-1

μ = 4πa02σ / kT
(σ : surface energy)

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

・ Equation of grain growth

Growth rate is independent of grain radius

2-4. Dust formed in Type II-P SNeaverage radius
0.01 μm

Umeda & Nomoto+02

Condensation time

－ various dust species form
according to compositionof gas in each layer－ condensation time:
300-600d after explosion－ average radii: >~0.01 μm
Nozawa+03, ApJ, 598, 785

2-5. Size distribution of newly formed dust

－ C, SiO2, and Fe grains
have log-normal size
distribution,－ the other grain species
have power-law size
distribution

2-6. Total mass of dust formed
Nozawa+03, ApJ, 598, 785
SNe II-P (Z=0)

SNe II-P (Z=0)

Total dust mass increases
with increasing Mpr
Mdust = 0.1-1.5 Msun・ depletion factor
fdep (Mdust/Mmetal) = 0.2-0.3➔ almost all Mg, Si, and Fe
are locked in dust

➔ incorporation of C and O
into dust in MCs needed?

cf. fdep = 0.4-0.5 in the MW

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

He coreFSRSCD

3-1. Dynamics of dust

3-2. Erosion rate of dust by sputtering3-3. Erosion rate of dust by sputteringNozawa+06, ApJ, 648, 435

projectile: H+ + He+projectiles: O+・ erosion rate at T > 106 K:
da/dt ~ 10-6 nH μm yr-1 cm3・ destruction timescale by sputtering:τsput ~ 106 yr (1 cm-3/nH) (a/1.0 μm) yr

3-4. 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3-5. 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

3-6. Mass and size of dust ejected from SN II-PNozawa+07, ApJ, 666, 955

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)

at time of dust formation

after destruction of dust
by reverse shock3-7. Summary of dust production in CCSNe
・ 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 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 decreases
with increasing the ambient gas density
for nH,0 = 0.1-1 cm-3
SNe II-P ➔ Mdust = 0.1-0.8 Msun
(high enough to account for massive dust at high z)

3. Formation of dust grains invarious types of SNe

4-1. 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

4-2. Dependence of dust radii on SN type
SN IIbSN II-P0.01 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

4-3. 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

4-4. 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+10, 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)

5-1. Dust formation in Type Ia SN○ Type Ia SN modelW7 model (C-deflagration) (Nomoto+84; Thielemann+86)－ Meje = 1.38 Msun

－ E51 = 1.3－ M(56Ni) = 0.6 Msun

5-2. Dust formation and evolution in SNe Ia
average radius

Nozawa+11, ApJ, 736, 45

dust destruction in SNRs
0.01 μm

・ condensation time :100-300 days
・ average radius of dust :aave <~ 0.01 μm
・ total dust mass :Mdust ~ 0.1 Msun

newly formed grains arecompletely destroyed for
ISM density of nH > 0.1 cm-3
➔ SNe Ia are unlikely to be
major sources of dust

6. Summary of this talk・ SNe II-P can inject a large amount of dust (>0.1 Msun)－ almost all Mg, SI, and Fe atoms are trapped in dust
－ FIR observations of SNe support massive dust・ 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・ Observations of nearby young SNRs with SPICA will
be able to resolve the role of SNe as sources of dust