Are Type Ia supernovae importantsources of interstellar dust?
（Ia型超新星は星間ダストの重要な供給源か？）Takaya Nozawa(IPMU, University of Tokyo)
Collaborators:
K. Maeda (IPMU)
T. Kozasa (Hokkaido Univ.)
M. Tanaka (NAOJ)
K. Nomoto (IPMU)
H. Umeda (Univ. of Tokyo)

1-1. Introduction〇 Type Ia supernovae (SNe Ia)－ thermonuclear explosions of C+O white dwarfs withthe mass close to Chandrasekhar limit (~1.4 Msun)・ deflagration (Nomoto+76, 84)➔ subsonic wave, unburned C in the outer layer・ (delayed) detonation (Khokhlov 91a, 91b)
➔ supersonic wave, burning almost all C－ synthesize a significant amount of Fe-peak andintermediate-mass elements such as Si, Mg, and Ca➔ play a critical role in the chemical evolution➔ possible sources of interstellar dust?

1-2. Type Ia SNe are sources of dust?
〇 Suggestions on dust formation in SNe Ia－ SNe Ia may be producers of Fe grains(Tielens 98; Dwek 98)－ the isotopic signature of presolar type X SiC grains
can be explained if produced in SNe Ia (Clayton+97)〇 IR Observations of SNe Ia and Type Ia SNRs
－ no evidence for dust formation in normal SNe Ia－ no evidence for ejecta-dust in young Type Ia SNRs
Tycho SNR (Douvion+01, but see Ishihara+10)
Kepler SNR (Douvion+01, Blair+07)
young Type Ia SNRs in LMC (Borkowski+06, Seok+08)➔ shock-heated interstellar dust of < 10-2 Msun

1-3. Aim of our study〇 Questions

vs.

－ Are there any differences in formation process ofdust between SNe Ia and (Type II) CCSNe?

－ Is it possible for dust grains to form in SNe Ia ?

〇 Dust formation calculation in SNe Ia➔ chemical composition, size, and mass of dust thatcan condense in the ejecta of SNe Ia➔ dependence of dust formation process on SN types➔ implication on the outermost layer in SNe Ia➔ survival of newly formed dust against destruction
by the reverse shock2-1. Model of SNe Ia (1)〇 Type Ia SN model

elemental composition

C-deflagration W7 model(Nomoto+84; Thielemann+86)－ Meje = 1.38 Msun
－ Ekin = 1.3x1051 erg－ M(56Ni) = 0.6 Msun## M(56Ni) ~ 0.06 Msun intypical CCSNe－ stratified distribution(no mixing of elements)## This assumption is
supported observationally(e.g. Mazzali+08; Tanaka+11)

0.1 Msun of C and O
remained unburnedin the outermost layer
with MC/MO ~ 1

2-2. Model of SNe Ia (2)hydrodynamic model

red lines : SNe Ia
・ Meje = 1.38 Msun
・ Ekin = 1.3x1051 erg
blue lines : Type II-P SNe
・ Meje = 20 Msun
・ Ekin = 1.0x1051 erg
・ Menv = 13.2 Msun

－ The gas density in SNe
Ia is more than 3 ordersof magnitude lower thanthat in SNe II-P
－ The gas temperature in
SNe Ia decreases morequickly2-3. Calculation of dust formation〇 nucleation and grain growth theory(Nozawa+03, 08, 10)－ steady-state nucleation rate
2－ grain growth rate

－ sticking probability : αs = 1.0 and 0.1－ LTE condition : Td = T(newly formed dust has the same temperature as the gas)

The use of the same prescription enables the directcomparison with our earlier results for SNe II3-1. Results (1): Condensation time of dust
Condensation timeCondensation temperature－ different dust species
form in different layers
・ Fe and Ni grains cannot
condense significantly
・ SiC can never condense－ condensation time of dust
: tc = 100-300 days
Nozawa+11, ApJ, 736, 45(tc > ~300 days in SNe II)3-2. Results (2): Average radius of dust
SN Ia

SN II-P

0.01 μm
0.01 μm

SN IIbaverage radius of 0.01
dustμm: aave < ~0.01 μm
because of low densityof gas in the ejecta
Nozawa+11, ApJ, 736, 45

the radius of dust formedin H-stripped SNe is small

・ SNe IIb/Ia with thin/noH-env ➔ aave < 0.01 μm
・ SN II-P with massive
H-env ➔ aave > 0.01 μm

3-3. Results (3): Mass of each dust species
with molecule formation

with no molecule formation

0.03 Msun

0.07 Msun

T ≠Td
0.08 Msun

0.08 Msun

Maximum mass of dust formed in SNe Ia : 0.1-0.2 Msunref. 0.1-1.0 Msun for SNe IIFormation of C grain follows the presence of C atoms
Nozawa+11, ApJ, 736, 45

3-4. Survival of dust in Type Ia SNRsa－ 10-3 Msun of dust cansurvive for nH ~ 0.01 cm-3
but too low ISM density－ typical gas density
around SNe Ia➔ nH,0 = 1.0-5.0 cm-3
(Borkowski+06)

newly formed grains arecompletely destroyed for
ISM density of nH > 0.1 cm-3

SNe Ia are unlikely to be major sources of dust

4-1. Multi-wavelength view of Kepler SNR○ Kepler・ Type Ia or Ib

Gomez, Clark, TN, +11, MNRAS, accepted
70 μm

100 μm160 μm

250 μm350 μm500 μm・ t = 407 yr
・ d ~ 4.0 kpc(Blair+07)

・ radius of FS:103”(2.0 pc)
・ radius of RS:80”(1.6 pc)

850 μmCO・ ambient gas
density:n0 ~ 5.0 cm-3
At λ >= 160 µm, it is difficult to disentangle any SNRemission from the large-scale interstellar structure

6 cm

4-2. Origin of dust in Kepler
Hα and 70 μm

X-ray and 70 μm

Two-component dust
warm: 84 K, 3.5x10-3 Msun
cold: 19 K, 2.2 Msun

・ The dust originates from theshocked circumstellar medium

・ There is no evidence for a cool
dust component in the ejecta

warm

cold

4-3. Multi-wavelength view of Tycho SNR○ TychoGomez, Clark, TN, +11, MNRAS, accepted
CO18 cm

24 μm(Krause+07)

70 μm

100 μm160 μm・ radius of FS:251”(4.6 pc)
・ radius of RS:183”(3.4 pc)

250 μm350 μm500 μm・ Type Ia
・ t = 439 yr
・ d ~ 3.8 kpc

・ ambient gas
density:n0 ~ 3.0 cm-3
Two bright components in the NE and NW at 70 µm
corresponds to peaks in 24 µm emission

4-4. Origin of dust in Tycho
CO and 70 and 250 μm
X-ray and 70 μm

warm

Two-component dust
warm: 90 K, 8.6x10-3 Msun
cold: 21 K, 4.0 Msun

・ The dust originates from theshocked interstellar medium

・ There is no evidence for a cool
dust component in the ejecta

cold5-1. Comparison with theoretical calculations
・ Nozawa et al. (2011) model－ dust mass at dust formation
0.2 Msun for αs = 1 and nomolecular formation＊ observed dust masses：
3.1x10-3 Msun for Kepler
8.6x10-3 Msun for Tycho

dust mass at 400 (440) yr
8.8(8.4)x10-2 Msun for n=1 /cc
2.6(2.3)x10-2 Msun for n=3 /cc
1.7(1.4)x10-2 Msun for n=5 /cc➔ the surviving dust mass ishigher than observed ones

・ 0.1 Msun case withmolecular formation
dust mass at 400 yr
6x10-2 Msun for n=1 /cc
1x10-2 Msun for n=3 /cc
8x10-3 Msun for n=5 /cc

5-2. Comparison with theoretical calculations
・ IR emission region－ in Kepler95”-103” (1.8-2.0 pc)－ in Tycho
220”-251” (4.0-4.6 pc)

The model-predicted positionof newly formed dust~90” for Kepler (n0 ~ 5.0 cm-3)~190” for Tycho (n0 ~ 3.0 cm-3)➔ The positions of supernova
dust do not match emission
region seen with HerschelModel predicts theunshocked Fe grains➔ Herschel does notdetect any significant
mass of cool dust in
the inner ejecta

n = 3 cm-3

Summary－ C, silicate, Si, and FeS grains can condense in theejecta of SNe Ia at 100-300 days (>300 days in SNe II)－ Due to the low ejecta density, the average radii of dust
are below 0.01 μm, smaller than those in SNe II-P

－ The total mass of dust that can form in the ejecta ofSNe Ia is up to 0.1-0.2 Msun
－ For the IS density of nH,0 > 0.1 cm-3, the newly formed
grains are completely destroyed within SNRs
➔ SNe Ia are unlikely to be main producers of dust

－ Herschel observations do not find evidence for freshlyformed supernova dust in Kepler and Tycho SNRs

5. Conclusion
・ Herschel observations do not find evidence for freshlyformed supernova dust in Kepler and Tycho SNRs
➔ Type Ia SNe do not produce massive iron grains
・ warm dust in Kepler
dust mass of 3.1x10-3 Msun, which originates fromswept-up circumstellar dust
・ warm dust in Tycho
dust mass of 8.6x10-3 Msun, which originates fromswept-up interstellar dust・ The observed mass of warm dust is lower than themodel predicts➔ dust formation in SNe Ia may be inhibited, ornewly formed dust may be destroyed efficiently