Akio K. Inoue (Osaka Sangyo Univ.)

2010/4/29 1Mini-workshop on cosmic dust at IPMU

QSO at z=6.42

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Fan et al.(2003)

The most distant QSO found by Sloan Digital Sky Survey:

SDSS J1148+5251Redshift: z=6.42 (Bertoldi et al.2003; CO lines)Blackhole mass: 3x109 Msun(Willott et al.2003;MgII2799)

Cosmic age: 840 Myr at z=6.42In ΛCDM structure formation scenario, a QSO/SMBH with ~109 Msun at z~6 can be formed (Li et al.2007).

A huge amount of dust!

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Bertoldi et al.(2003)

SDSS J1148+5251 (z=6.42)Blackhole mass: 3x109 Msun

(Willott et al.2003)Dust mass: 2x108 MsunGas mass: 3x1010 Msun

(Dwek et al.2007)

Color(green—red—yellow): SDSS z-band (~9134 A)

Pink: IRAM/MAMBO-2 250 GHz (1.2mm dust continuum)Blue: VLA 1.4 GHz (21cm)

Dust-free z~6 QSOs?

2010/4/29 Mini-workshop on cosmic dust at IPMU 4Jiang et al.(2010)~

Hot

dust

mas

s/st

ella

r m

ass

A correlation between BH mass and dust abundance is found at z~6!

Smaller BHs are before dust production phase?

What is the origin of dust?~108 Msun dust by the cosmic age 840 MyrIn the present-day Milky Way, Asymptotic Giant Branch (AGB) stars produce the most of ‘stardust’ (e.g., Draine 2009).

Time-scale to evolve to the AGB phase: ~1 GyrDust supply by SNe of short-lived (<10 Myr) massive stars? (Dwek et al.2007)

Dust yield > 1 Msun per 1 SN is required.Theoretical prediction is ~0.1-1 Msun per 1 SN (Nozawaet al. 2007)Observations give <0.01-0.1 Msun per 1 SN

~5 Msun stars evolve to AGB phase enough quickly, so these stars can supply enough dust? (Valiante et al.2009)How about dust growth in the ISM? (Draine2009)

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Chemical+dust evolution modelAn extension of galaxy chemical evolution modelSince Dwek & Scalo (1980), there are some groups.

In Japan, Hirashita (1999a,b,c,2000), Inoue (2003)

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ISM

METAL DUST

STAR

REMNANT

GALAXY IGM

Chemical+dust evolution model

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ddac

d

SN

dd

d

ZZZZ

ISM

*

)1( DUST

METAL

ISM

STAR

OIMMYDSdt

dM

OIYZSdt

dM

OIRSdt

dM

RSdt

dM

Chemical+dust evolution model

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ddac

d

SN

dd

SF

dd

ZZZSF

ZZ

SF

ISMISM

SF

ISM

SF

ISM*

)1( DUST

METAL

ISM

STAR

OIMMYMdt

dM

OIYMdt

dM

OIRMdt

dM

MSRMdt

dM

Computational settingOne-zone, one-phase ISMWith primordial gas infall, without outflowSF timescale = Infall timescale = 1x108 yrTotal gas reservoir = 1x1012 Msun

Dust production by SNe and AGB stars （md=1x10-2 Msun）Finite stellar life-time

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ISM

METAL DUST

STAR

REMNANT

GALAXY IGM

Computational result

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SFR: dotted line

Dust masssolid line: mSN=1x103 Msun

ac,0=1x107 yr

dashed line:mSN=1x103 Msun

ac,0=5x106 yr

dot-dashed line:mSN=5x102 Msun

ac,0=1x107 yr

SFR

Dust mass

Dust mass

Dwek et al.(2007)

Comparison of time-scales: 1

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ac

d

SN

d

*

d

SF

dd )1(MMMMdt

dM

yr 10110 8SN*SF

12/11

37

ac 02.0K 100cm 100m 1.0yr 103 ZTna

)1/(acSN*SF

In a starburst galaxy (or z~6 QSO)

Balance between SN destruction and ISM growth determines the dust amount and dust-metal ratio (δ).

Comparison of time-scales: 2

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ac

d

SN

d

*

d

SF

dd )1(MMMMdt

dM

yr 10510 9SN*SF

12/11

37

ac 02.0K 100cm 100m 1.0yr 103 ZTna

)1/(acSN*SFBalance between SN destruction and ISM growth determines the dust amount and dust-metal ratio (δ).

In the present-day Milky Way

Dust-free QSO?

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0.002Mstar

thick: M=1x1012 Msunthin: M=2x1012 Msun

Dust masssolid line: mSN=1x103 Msun

ac,0=1x107 yr

dashed line:mSN=1x103 Msun

ac,0=5x106 yr

dot-dashed line:mSN=5x102 Msun

ac,0=1x107 yr

before accretion growth activates

after accretiongrowth activates

SummaryDust growth in the ISM can account for the observed huge amount of dust in z~6 QSOs.Dust amount is determined by the balance between SN destruction and ISM growth after the ISM growth becomes effective:

A universal mechanism to determine the dust mass.‘Dust-free’ QSOs recently found at z~6 may be in the phase before the ISM growth becomes effective.

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‘Stardust’ production

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dmmtSmmtZmmtYm

tm])[()()])([,()( lf)( lfdd

u

Stellar dust yield(SNe and AGBs)

sun2

d 10 Mm(Nozawa et al.2007, Zhukovska et al.2008)

Instantaneous recycling approximation (or a constant SFR):

*

d3

SF

ISM3

dd

10)(10

)()()( u

t

MMtS

dmmmtStYm

m

3SF* 10D

(for Salpeter IMF)

Destruction by SN shocks

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SNSN

ISMSN

SN

dSNSN

SN

d

RmMMRDm

dtdM

(e.g., McKee 1989)SN occurrence rate:

SF

ISM22

40

8 lfSN

10)(10

])[()()(

MtS

dmmtSmtRM

M

Effective shocked mass:

sun3

SN 10 Mm10

SFSN

(e.g., McKee 1989)

Growth in the ISM

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ac

dZ

gasZZ

2d

ac

d )1(MsaNdt

dM

)1(4

3gasdZ

gasZ3

dd Z

aMN

Dust particle number: Density of gas-phase metals:

12/11

37

gasZ2

3

ac

02.0K 100cm 100m 1.0yr 103

3

4

ZTna

Zsa

a

Z ( =3 g/cm3, sZ=1, 56Fe case)

: depletion factor(dust-metal mass ratio)

A universal mechanism?Both in the current Milky Way and in z~6 QSO, the balance between SN destruction and ISM growth is likely to determine the dust amount.

a universal mechanism?How about the composition and size distribution?

What kind of dust species grow by the accretion process?What is the effect of different “seeds”?

What about the accretion time-scale? More rapid? (Draine 2009)

Effect of charge? (Weingartner & Draine 2001)ISM turbulence? (Yan et al.2004)

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