2016/02/23

Properties of dust ejectedfrom supernovae
Takaya Nozawa(National Astronomical Observatory of Japan)

Contents:- Introduction of dust formation in SNe- Properties of dust from theoretical works on dust
formation and processing in SNe- Observations of dust composition and size in SNe

1-1. Introduction〇 Supernovae (SNe) are major sources of dust?
- abundant metal (metal : N > 5)
- low temperature (T < ~2000 K)- high density (ni > ~106 cm-3)- mass-loss windsof AGB stars- expanding ejectaof SNe‐ contribution of dust mass from AGB stars and SNe
N(SNe) / N(AGB stars) ~ 0.05-0.1 (Salpeter IMF)

Mdust = 0.01-0.05 Msun per AGB star (e.g., Zhukovska & Gail 2008)
Mdust = 0.1-1.0 Msun per SN (e.g., Nozawa+2003, 2007)‐ huge amounts of dust grains (>108 Msun) at redshift z > 5➔ 0.1 Msun of dust per SN is needed to be ejected (Dwek+2007)
what composition, size, and mass of dust are ejected by SNe?

1-2. 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1-3. Summary of observed dust mass in CCSNe

missing cold dust?

young SNRs

Matsuura+2011

Type II-P SNeBalow+2010

Gomez+2012

swept-up IS dust?

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

1-3. Summary of observed dust mass in CCSNe

missing cold dust?

young SNRs

Type II-P SNe

swept-up IS dust?

There are increasing pieces of evidence that massive
dust in excess of 0.1 Msun is formed in the ejecta of SNe

1-4. Formation and processing of dust in SNe
Nozawa 2014, Astronomical Herald~1-3 yrs~1000 yrs

Destruction efficiency of dust grains by sputtering in thereverse shocks depends on their initial size
The size of newly formed dust is determined by physicalcondition (gas density and temperature) of SN ejecta

1-5. Achievement and issues on SN dust〇 What we have understood isCore-collapse supernovae can produce a large amountof dust in excess of ~0.1 Msun in the expanding ejecta〇 What we have not understood yet is1) when the observed massive dust was formed?
➜ Cause of difference in dust mass in MIR and FIR2) What composition and size distribution of dust are?
➜ Critical to the yield of dust finally ejected from SNe

2. Theoretical works on formationand processing of dust in SNe2-1. Dust formation in Type II-P SNe
Nozawa+2003, ApJ, 598, 785〇 SN model (Population III SNe) (Umeda & Nomoto 2002)‐SNe II ： MZAMS = 13, 20, 25, 30 Msun (E51=1)
after 600 days

‐layered elemental distribution in the metal-rich He core‐no mixing of elements within the He-core‐gas density: ρ ~ 10-14-10-13 g/cm3 ➜ n ~ 108-1010 /cm3

2-2-1. Grain species considered in this study〇 dust formation theory‐nucleation‐grain growth
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
Steady-state nucleation rate: Js

Supersaturation ratio: S

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. Dust formed in Type II-P SNeaverage radius

0.01 μm

C / O < 1 ➔ all C atoms are locked up in CO
C / O > 1 ➔ all O atoms are locked up in CO
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

2-4. 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‐Size distribution summed up over all grain species is roughly
described by a broken power-law with the index of -2.5 and -3.5
‐Size distribution of dust in mass has a peak around 0.1-1 µm

Destruction of dust grains by
SN reverse shocksT = (1-2)x104 K
nH,0 = 0.1-1 cm-3

He coreFSRSCD

2-5-1. Time evolution of SNRs

2-5-2. Dynamics of dust

2-5-3. Erosion rate of dust by sputtering

2-6. Evolution of dust in SNRs
Model : Mpr= 20 Msun (E51=1), nH,0 = 1 cm-3
dust trajectories

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 shellevolution ofdust radiiaini = 1 μm (dashed lines)➔ injected into the ISMNozawa+07, ApJ, 666, 955

2-7. Dust mass and size ejected from SNe II
Nozawa+07, ApJ, 666, 955

SNe II-P

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 (> 0.1 μm)

2-8. Conclusions from theoretical works
1) When the observed massive dust was formed?
➜ within 3 years after SN explosion
2) What composition and size distribution of dust are?
‐composition: carbon, silicate, oxide, pure iron …
‐size (distribution)- at the formation ➜ a few A to ~1 µm (broken power-law)- after destruction ➜ biased to larger than ~0.1 µm‐dust mass
- at the formation: 0.1-1.3 Msun
- after destruction: 0.07-0.8 Msun

A-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

A-2. Dependence of grain radii on SN type
SN IIbSN II-P

0.01 μm- condensation time of dust
300-700 days after explosion- the radius of dust formed in
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

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

stellar-wind CSM (ρCSM ∝ 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 the hot gas
that was swept up by the reverse shocks➔ small radius of newly formed grains➔ early arrival of reverse shock at dust-forming region
Nozawa+10, ApJ, 713, 356

A-4. IR emission from dust in Cas A SNRAKARI 90 μm image (color)・ 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)

3. Observations of compositionand size of dust in SNe
1) When the observed massive dust was formed?
2) What composition and size distribution of dust?

3-1. Revisiting dust mass formed in SN 1987A
775 day

8515 day- dust mass ~ 0.002 Msun

Wesson+15- dust mass ~ 0.7 Msun
- dust radius ~ 0.2 µm
large radius is required tohave Tdust ~ 20 K in LMC

3-2. Dust mass from line profiles in SN 1987A
OI 6300

Bevan & Barlow 2016

At 714 day
・ dust mass < 3x10-3 Msun(< 0.07 Msun if silicate)・ grain radius > ~0.6 µm

3-3. Evolution of dust mass in SN 1987A
It seems to be difficult that dust
continues to form in later epochs
at which gas density is low

At 615 and 714 day
・ dust mass: ~0.4 Msun
Dwek & Arendt 2015, ApJ, 810, 75

・ silicate-dominated3-4. Composition of dust formed in SNe
first detection of silicate in SN

775 daysilicate
Wesson+15, SN 1987A

8515 daycarbonKotak+09, SN 2004et
Matuura+2011, SN 1987A

3-5. Composition of dust in Cas A SNR

Douvion+01- glassy carbon- FeO, Al2O3Rho+08- MgSiO3- Fe, FeS, Si- Mg-silicate- FeO, SiO2

various grain species exist in each place (layer)

3-6. Dust properties in one knot of Cas A SNR

to cause large extinction,large dust mass is needed

cool dust component
Lee, Koo et al. 2015, ApJ, 808, 98

Far-side is more obscured
than near-side E(J-H) = 0.23

➜ Fe with a < 0.01 µm(or large Si dust)

Fλ ∝ 4 Mdust κemis(λ) πBλ(Tdust)

3-7. Conclusions from observational works
1) When the observed massive dust was formed?
➜ under debate‐dust mass gradually increases throughout 25 years‐dust formation must be finished within a few years
2) What composition and size distribution of dust are?
‐composition: carbon, silicate, oxide, pure iron …
➜ consistent with the theoretical prediction‐size (distribution)- SN 1987A ➜ relatively large above 0.1 µm?
- Cas A ➜ small Fe (< 0.01 µm) or large silicon?
not well constrained for the other species