Origin and Nature of Dustin the Early Universe
Takaya Nozawa
・Institute for the Physics and Mathematics of the Universe
・Graduate School of Science, Hokkaido UniversityCollaborators;
T. Kozasa (Hokkaido Univ.), H. Umeda (Univ. of Tokyo)
H. Hirashita (ASIAA), K. Maeda (IPMU), N. Tominaga (NAOJ)
K. Nomoto (Univ. of Tokyo, IPMU), A. Habe (Hokkaido Univ.)
E. Dwek (NASA Goddard Space Flight Center)
T. T. Takeuchi (Nagoya Univ.), T. T. Ishi (Kyoto Univ.)
1

Contents of this talk
1. Introduction
2. Dust formation in primordial SNe

3. Dust evolution in primordial SNRs
4. Role of dust in the early universe
5. Extinction curves expected at high redshifts21. Introduction31-1. A large amount of dust at z > 5・ 30% of z ＞ 5 quasars have shown the presence of large
amounts of dust grains with mass larger than 10^8 Msun
(Bertoldi et al. 2003; Priddey et al. 2003; Robson et al. 2004;
Beelen et al. 2006; Wang et al. 2008a, 2008b)
SDSS J1148+5251 at z=6.4

a rapid enrichment with dust
formed in the ejecta of SNe
180 K, β=040 K, β=2Robson et al.
(2004, MNRAS, 351, L29)

Dust of 0.1-1 Msun per SN isrequired to form to explain alarge content of dust at high-zgalaxies(Morgan & Edmunds 2003,Maiolino et al. 2006;
Dwek et al. 2007)4

1-2. Extinction curve of high-z quasar
SDSS J1048+4637 at z=6.2
Broad absorption line (BAL) quasars
NICS at the Italian TNG

Maiolino et al.
(2004, Nature, 431, 533)

different dust properties fromthose at low redshifts5

1-3. Role of dust in the early universe
・ Dust absorbs stellar light and re-emits it by thermal radiation➔ plays a crucial role in interpreting the SFR and the IMFof the early generation of stars from high-z observations(e.g., Loeb & Haiman 1998)

・ Dust has great impacts on the formation processes of stars－ providing additional cooling pathways of gas throughthermal emission (e.g., Schneider et al. 2003, Omukai et al. 2005)－ forming molecules (mainly H2) on the surface(e.g., Cozax & Spaans 2004)－ controlling the energy balance in the interstellar medium

61-4. Aim of our study
In the previous studies, the composition and size ofdust are assumed to be the same as those in Galaxy,
and the amount is treated as a parameter
Absorption and thermal emission by dust grains
are sensitive to the composition, size, and amount

It is essential to clarify the properties ofdust in the early epoch of the universe!
We aim at revealing the composition and size,amount of dust by treating self-consistently theformation and destruction processes of dust7

1-5. Sources of dust in the early universe
・ At z > 5, the main formation sites of dust are considered
to be in the ejecta of supernovae (SNe)・ first stars (Population III stars) ➔ very massive
M =100-500 Msun

In the early universe
・ Type II SNe (SNe II)；Mpr=8-40 Msun
・ pair-instability SNe；Mpr=140-260 Msun
(Heger et al. 2003, 591, 288)

2. Dust Formation in Primordial SNe
at ~1 days
He-coreH-envelope

NS or BH
He–layer (C>O)
O–Ne-Mg layer
Dust formation
Si–S
layeryears
at ~1-3
after explosion
Fe–Ni layer

2-1. Dust formation in primordial SNe (1)Todini & Ferrara (2001, MNRAS, 325, 726)・ SNe II (M = 12-30 Msun, Z = 0-0.02) by Woosley & Weaver (1995)
・ one-zone model within He core・ formation and destruction of CO and SiO molecules
・ initial gas density and temperature for SN 1987A

Mpr = 22 Msun

Mdust = 0.1-1 Msun

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2-2. Dust formation in primordial SNe (2)Nozawa et al. (2003, ApJ, 598, 785)・ SNe II (M = 13, 20, 25, 30 Msun, Z=0)
PISNe (M = 150, 170, 200 Msun)
by Umeda & Nomoto (2002)
・ mixing of elements within He-core ➔ two extreme cases
unmixed case (onion-like structure)
uniformly mixed case (retaining the density profile)・ gas temperature; solving radiative transfer calculation
・ formation of CO and SiO molecules is complete
C / O > 1 ➔ all O atoms are locked into CO
C / O < 1 ➔ all C atoms are locked into CO
Si / O < 1 ➔ all Si atoms are locked into SiO

112-3. Dust formed in the unmixed ejecta

・ Various dust species (C, MgSiO3, Mg2SiO4, SiO2, Al2O3, MgO,Si, FeS, Fe) form in the unmixed ejecta, reflecting the elemental
composition in each layer.

・ C, SiO2, and Fe grains are lognormal-like size distribution withrelatively large radii, while other grains are power-law-like one.
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2-4. Dust formed in the mixed ejecta

・ Because O atoms are richer, only silicate（MgSiO3, Mg2SiO4, SiO2）
and oxides （Fe3O4, Al2O3） form.
・ The size distribution of each dust species except for Al2O3 islognormal-like13

2-5. Total mass of dust formed
SNe IIPISNe

Schneider et al. (2004)

・ Total dust mass increases with increasing progenitor mass
SNe II ： Mdust = 0.1-2 Msun PISNe ： Mdust = 10-60 Msun
・ Dust mass for the mixed case is generally larger than for
the unmixed case14

2-6. Extinction curves from SN dust
TF01 dust model

Maiolino et al.
(2004, Nature, 431, 533)

N+03 dust model

Hirashita et al.
(2005, MNRAS, 357, 1077)

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3. Dust Evolution in Primordial SNRs
T = (1-2) x104 K
nH = 0.1-1 cm-3

He coreFSRSCD

3-1. Bianchi & Schneider’s calculation
Bianchi & Schneider(2007, MNRAS, 378, 973)

semi-analytical model
neglecting motion of dustt < ~10^5 yr

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3-2-1. Time evolution of shock wave

3-2-2. Initial condition for shock wave
○ SN ejecta models (Umeda & Nomoto 2002)
・ SNe II : Mpr=13, 20, 25, 30 Msun (E51=1)
・ PISNe : Mpr=170 (E51=20), 200 Msun (E51=28)○ The ambient medium
・ primordial composition (uniform)・ gas temperature ; T = 104 K・ gas density ; nH,0 = 0.1, 1, and 10 cm-3
(e.g., Kitayama et al. 2004; Machida et al. 2005)
The calculation is performed from 10 yr up to ~106 yr

3-3. Dynamics of dust
・ dust model : results of dust formation calculations
・ treating (spherical) dust grains as test particles
・ neglecting the effects of charge of dust

3-4-1. Erosion rate of dust by sputtering3-4-2. Erosion rate of dust by sputteringfor primordial composition gas

for oxygen ions・ the erosion rate by sputtering quickly increases above 10 5 K
and peaks at 107 -108 K
・ da / dt ～ 10-6 nH μm yr-1 cm3 for T > 106 K and primordial gas

3-5-1. Temperature and density of gas(Nozawa et al. 2007, ApJ, 666, 955)

Model : Mpr=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 this hot
gas are eroded by sputtering23

3-5-2. Evolution of dust in SNRs
(Nozawa et al. 2007, ApJ, 666, 955)

Model : Mpr=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 into24the ISM

3-5-3. Size distribution of surviving dust

The size distribution of surviving dust is greatly deficient insmall-sized grains, compared with that at its formation➔ Dust in the early universe is dominated by large grains25

3-5-4. Total mass of surviving dust

Total mass of dust surviving the destruction for Type II SNRs;
0.1-0.8 Msun for the unmixed grain model (nH,0 = 0.1-1 cm-3)
0.06-0.7 Msun for the mixed grain model (nH,0 = 0.1 cm-3)➔ high enough to explain dust content at high-z galaxies(Morgan & Edmunds 2003, Maiolino et al. 2006; Dwek et al. 2007)
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4. Role of Dust in the Early Universe27

4-1. Critical metallicity

Schneider et al. (2006, MNRAS, 378,973)
28

4-2. 3-D simulation of star-forming cloud

Tsuribe & Omukai (2006, ApJ, 378,973)29

4-3. Impacts of dust on Pop II.5 starsPopulation II.5 stars : the 2nd-generation stars formed in
the dense shell of Pop III SNRs
(Mackey et al. 2003; Salvattera et al. 2004; Machida et al. 2005)

dust grains surviving the destruction but not injected
into the ISM are piled up in the dense shell in 105-106 yr↓
・ elemental composition of these
piled-up grains➔ elemental abundance ofPopulation II.5 stars

comparing with observations ofHMP and UMP stars30

4-4. Elemental abundance in the shell (1)metallicity of shell
Z > Zcr = 10-6 Z☉[Fe/H] = -5.62 (HE0107-5240; Collet et al. 2006)[Fe/H] = -5.96 (HE1327-2326; Frebel et al. 2008)[Fe/H] = -4.75 (HE0557-4840; Noris et al. 2007)
3-D corrected31

4-5. Elemental abundance in the shell (2)－6 ＜ [Fe/H] ＜－5
0 ＜ [Mg, Si/Fe] ＜ 2↓

Elemental composition ofdust piled up in the shell
can reproduce abundance
patterns in HMP stars

The transport of dust segregated from metal-rich gas
can be responsible for the elemental composition ofPopulation II.5 stars formed in the dense SN shell.
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5. Extinction Curves Expected
at high redshifts

335-1. Flattened extinction curves

flat extinction curve at high redshifts !

Hitashita et al. (2008, 384, 1725, MNRAS)
34

5-2. Extinction in high-z BAL quasars

Priddey et al. (2003, MNRAS, 344, L74)

Maiolino et al. (2004, A&A, 420,889)35

5-3. Extinction curves of low-z AGNs

Gaskell et al.
(2004, ApJ, 616, 147)
Willot (2005, ApJ, 627, L201 )Gaskell & Benker (2008, astro-ph/0711.1013)
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5-4. Extinction curves from GRBs

Heng et al. (2004, ApJ, 681, 1116)

37
Stratta et al. (2005, A&A,441, 83)

5-5. Extinction curves from GRBsGRB 050904 at z=6.3

Li et al. (2008, ApJ, 685, 1046)

Stratta et al. (2007, ApJ, 661, L9)

Li et al. (2008, ApJ, 678, 1136)
coagulation of grains in dense clouds
evaporation of smaller grains by GRB
destruction of small grains by shock38

Summary of this talk1. The fate of newly formed dust within primordial SNRs
strongly depends on the initial radii and compositions.
2. Size distribution of dust surviving in SNRs is weightedto large size.
3. Dust grains in the early universe play crucial roles in
the formation of metal-deficient low-mass stars.

4. Dust formed in Population III stars has great impacts on
the composition and formation of Population II.5 stars.
5. Extinction curves in the early universe are expected tobe flat.
39