2014/02/19

Formation and Destruction
Processes of Dust in Supernovae
Takaya Nozawa(Kavli IPMU, University of Tokyo）
Main collaborators:
T. Kozasa, A. Habe (Hokkaido University)
K. Maeda (Kyoto Unviersity), K. Nomoto (Kavli IPMU)
H. Umeda (University of Tokyo) , M. Tanaka (NAOJ)
N. Tominaga (Konan University)

0-1. Sources of dust in our Galaxy
Milky Way (optical)

Milky Way (infrared)

SNe are important sources of interstellar dust?
－ number (occurrence) ratio of SNe to AGB starsn(SNe) / n(AGB stars) ~ 0.05-0.1
Mdust = 0.1-1.0 Msun per SN (Nozawa et al. 2003; 2007)
Mdust = 0.01-0.05 Msun per AGB (Zhukovska & Gail 2008)

0-2. Formation site of dust
○ Formation sites of dust
・ abundant metal (metal : Z > 5)・ low gas temperature (T < ~2000 K)・ high gas density (n > ~106 cm-3)－ mass-loss winds of AGB stars－ expanding ejecta of supernovae－ molecular clouds (grain growth only)－ red giant, W-R stars, novae, protoplanetary disk …
➔ relative contribution of these sources is unclear!

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

swept-up IS dust?

Kepleryoung SNeTycho

by 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

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

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. Emission and absorption efficiency of dust
○ Thermal radiation from a dust grain
Fλ ∝ 4πa2 Qemis(a,λ) πBλ(Tdust) # Qemis = Qabs
carbonsilicate(Qemis/a) is independent of aFλ ∝ 4πa3 (Qemis[a,λ]/a) πBλ(Tdust)∝ 4 Mdust κemis(λ) πBλ(Tdust)➔ IR emission is derived given Mdust, κabs, and Tdust1-4. Origin of IR emission from SNe
Dust formation in the ejecta

Dust formation in dense shellIR echo by CS dust

Shock heating of CS dust

1-5. Evidence for dust formation in SN 2006jcKHJ
Di Calro+08
Tominaga+08

・ brightening of IR
・ rapid decline of optical light・ blueshift of emission lines
formation of CO and SiO molecules(more robust if SiO are depleted)

Tominaga+08

Smith+08

1-6. Composition of dust formed in SNe
IS dust : carbonaceous grain andsilicate (MgSiO3, MgFeSiO4, …)
SN 2004et

SN 2006jc

silicate➔ 1750 K

silicate

carbon

SN 2004et, Kotak+09

carbon➔ 1660 K

SN 2006jc, Smith+08

1-7. Dust formation in Type IIn SN 2010jl
carbonT = 1300 K

MgSiO
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 Type IIb SNe

2-0. How do dust grains form?
chemical approachgaseous atoms nucleation approach

molecules
formation ofseed nuclei???
large molecules
dust grains

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. Formulation of dust formationc1

c2

J2c3J3αn-1c1cn-1 cnJnβncn

・ master equations

2-3. 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 )2-4. Basic equations for dust formation
・ Equation of mass conservation

・ Equation of grain growth

Growth rate is independent of grain radius

2-5. Dust formation calculation in the ejecta○ Dust formation calculation－ non-steady nucleation andgrain growth theory(Nozawa et al. 2003)○ SN IIb model(SN1993J-like model)－ MH-env = 0.08 Msun
MZAMS = 18 Msun
Meje = 2.94 Msun
－ E51 = 1－ M(56Ni) = 0.07 Msun
〇 SN II-P model : MH-env = 13 Msun, MZAMS = 20 Msun, E51 =1(Umeda & Nomoto 2002)

2-6. Birth of dust in the ejecta of Cas A
mass distribution

condensation time

－ condensation time of dust
300-700 d after explosion－ total mass of dust formed
・ 0.167 Msun in SN IIb
Mc=0.07 Msun
Msilcate=0.08 Msun
・ 0.1-1 Msun in SN II-P

2-7. Dependence of dust radii on SN type
SN IIbSN II-P

0.01 μm

SN Ib (SN 2006jc)(Nozawa et al. 2008)

The radius of dust formedin H-stripped SNe is small－ SN IIb and SN Ib/Ic without
massive H-env➔ adust < 0.01 μm－ SN II-P with massive H-env➔ adust > 0.01 μm

3. Dust Destruction in Cas A

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 Heprojectile: 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. Calculation of dust evolution in SNRs
○ Dust evolution calculations (Nozawa et al. 2006, 2007)－ spherical symmetric hydrodynamic calculation based on
the ejecta model of the SN IIb－ treating dust as a test particle
・ erosion by sputtering
・ deceleration by gas drag・ collsional stochastic heating－ density profile of CSM

nH(r) = nH,1 (r / r1)-2 /cc= 1 /cc for nH < 1 /cc
r1 = r(at 10 yr) = 1.2x1018cm
nH,1 = 30, 120, 200 /cc(➔ dM/dt = 2.0, 8.0, 13x10-5 Msun/yr for vw=10 km/s)

3-6. Fate of dust in Cas A SNR
nH,1=120/cc

・ All of the dust grains in Cas A would be destroyed in
the shocked gas within the SNR before ~2x104 yr➔ small grain size of newly formed dust
➔ early arrival of the reverse shock at the He coreH-deficient SNe may not be major contributors of dust
・ 0.01-0.8 Msun of dust survive for SNe II-P (Nozawa+2007)

3-7. Comparison with observations of Cas A－ MIR, d = 0.008 Msun
(Mshocked, d ~ 0.1 Msun)－ dM/dt = 8x10-5 Msun/yr➔ dM/dt ~ 2x10-5 Msun/yr for
Cas A (Chevalier & Oishi 2003)➔ dM/dt = (3-4)x10-5 Msun/yrfor 93J (Suzuki & Nomoto1995)

3-8. Contribution from unshocked dust

Sibthorpe et al. 2009

observed IR SED canbe well reproduced！
↑・ Md,warm ~ 0.008 Msun
・ Md,cool ~ 0.07 Msun
with Tdust ~ 40 K

AKARI reduced 90μm image➔ centrally peaked cool
dust component↓Md,cool = 0.03-0.06 Msun
with Tdust = 33-41 K

Summary1) Birth of Dust in the ejecta of Cas A
Dust formed in Cas A was formed at 300-700 days after
the explosion with adust < 0.01 μm and Mdust = 0.167 Msun

2) Brightening of dust in the shocked hot gas
Model of dust destruction and heating in Type IIb SNR
can reasonably reproduce the observed SED of Cas A;
Md,warm = 0.008 Msun, Md,cool = 0.07 Msun
dM/dt = ~8x10-5 Msun/yr3) Fate of dust in Cas A SNR
Small dust grains in Cas A will be completely destroyedin the shocked gas without being injected into the ISM