2014/04/21

超新星爆発時におけるダスト形成研究の現状
野沢 貴也（Takaya Nozawa）(National Astronomical Observatory of Japan)
Main collaborators:
T. Kozasa, A. Habe (Hokkaido University)
K. Maeda (Kyoto University), K. Nomoto (Kavli IPMU)
H. Umeda (University of Tokyo) , M. Tanaka (NAOJ)
N. Tominaga (Konan University)

0-1. 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 ejectaof 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 (e.g., Nozawa et al. 2003, 2007)

1. Observations of Dust Formationin SNe (and SNRs)

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

Cas A

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

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

Cas A

young SNRs
Gomez+2012

Matsuura+2011
Balow+2010

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. ALMA reveals dust formed in SN 1987A
SED of 25-years old SN 1987A

2 arcsec

Indebetouw+2014

ALMA spatially resolves cool(~20K) dust of ~0.5 Msun formed inthe ejecta of SN 1987A➔ SNe could be production
factories of dust grains

1-3. Composition of dust formed in SNe
IS dust : carbonaceous grain andsilicate (MgSiO3, MgFeSiO4, …)
SN 2004etSN 2006jcsilicate➔ 1750 K

silicate

carbon

SN 2004et (Kotak+09)

carbon➔ 1660 K

SN 2006jc (Smith+08)

1-4. Dust formation in Type IIn SN 2010jlcarbon
T = 1300 KMgSiO
3 grains
silicate
T = 1450 K

Dust in SN 2010jl
・ carbon grains
・ grain radius: <0.1μm(possibly <0.01 µm)
・ dust mass: ~10-3 Msun
Maeda, TN, et al. 2013

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. Formulation of dust formation
c1c2

J2

c3

J3

αn-1c1cn-1 cnJnβncn

・ master equations

2-2. Steady-state nucleation rate
・ steady-state nucleation rate: Js➔ assuming Js = J2 = J3 = ・・・ = J∞

where
μ = 4πa02σ / kT
σ：surface tension

S : supersaturation ratio( S = p1 / p1v )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 formation in primordial SNe
Nozawa+2003, ApJ, 598, 785〇 Population III SNe model (Umeda & Nomoto 2002)‐SNe II ： MZAMS = 13, 20, 25, 30 Msun (E51=1)‐PISNe ： MZAMS = 170 Msun (E51=20), 200 Msun (E51=28)‐nucleation and grain growth theory (Kozasa & Hasegawa 1987)‐no mixing of elements within the He-core‐complete formation of CO and SiO

2-5. Dust formed in Type II-P SNeaverage radius

0.01 μm

condensation time‐a variety of grain species cancondense according to elemental
composition in each layer‐ condensation time:
300-600d after explosion‐ average grain radii: >~0.01 μm
Nozawa+03, ApJ, 598, 785

2-6. Size distribution of newly formed dust
Nozawa+2003, ApJ, 598, 785‐C, SiO2, and Fe grains have lognormal-like size distribution,
while the other grains have power-law size distribution‐The composition and size distribution of dust formed are almost
independent of types of supernova## average grain radius is smaller for PISNe than SNe II-P

2-7. Total mass of dust formed in the ejecta
SNe II‐Total mass of dust is higher for a higher progenitor mass (MZAMS)
SNe II ： mdust = 0.1-1.5 Msun, mdust / mmetal = 0.2-0.3
PISNe ： mdust = 10-30 Msun, mdust / mmetal = 0.3-0.4‐almost all Fe, Mg, and Si are locked up in dust grains, whilemost of C and O remain in the gas-phase (such as CO)➔ dust-to-metal mass ratio is not high for SNe II

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

He coreFSRSCD

3-1. Time evolution of SNRs

3-2. Dynamics of dust

3-3. Erosion rate of dust by sputtering3-4. Erosion rate of dust by sputtering
Nozawa+2006, ApJ, 648, 435

projectile: H and He

projectile: 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

3-5. 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3-6. Evolution of dust in SNRsNozawa+07, ApJ, 666, 955

Model : Mpr= 20 Msun (E51=1)
nH,0 = 1 cm-3
Dust grains in the He core
collide with reverse shockat (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

3-7. Dust mass and size ejected from SN II-PPISNe
SNe II

total mass of dust surviving thedestruction in Type II SNRs;
0.07-0.8 Msun (nH,0 = 0.1-1 cm-3)
size distribution of dust after theshock-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3-8. Summary of dust production in Pop III SNe‐Various grain species can condense in the ejecta➔ almost all Fe, Mg, and Si are locked up in grains‐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
➔ significant contribution to dust budget at high z