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Akio K. Inoue (Osaka Sangyo Univ.)
2010/4/29 1Mini-workshop on cosmic dust at IPMU
QSO at z=6.42
2010/4/29 2Mini-workshop on cosmic dust at IPMU
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!
2010/4/29 Mini-workshop on cosmic dust at IPMU 3
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)
2010/4/29 Mini-workshop on cosmic dust at IPMU 5
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)
2010/4/29 6Mini-workshop on cosmic dust at IPMU
ISM
METAL DUST
STAR
REMNANT
GALAXY IGM
Chemical+dust evolution model
2010/4/29 Mini-workshop on cosmic dust at IPMU 7
ddac
d
SN
dd
d
ZZZZ
ISM
*
)1( DUST
METAL
ISM
STAR
OIMMYDSdt
dM
OIYZSdt
dM
OIRSdt
dM
RSdt
dM
Chemical+dust evolution model
2010/4/29 Mini-workshop on cosmic dust at IPMU 8
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
2010/4/29 Mini-workshop on cosmic dust at IPMU 9
ISM
METAL DUST
STAR
REMNANT
GALAXY IGM
Computational result
2010/4/29 Mini-workshop on cosmic dust at IPMU 10
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
2010/4/29 Mini-workshop on cosmic dust at IPMU 11
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
2010/4/29 Mini-workshop on cosmic dust at IPMU 12
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?
2010/4/29 Mini-workshop on cosmic dust at IPMU 13
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.
2010/4/29 Mini-workshop on cosmic dust at IPMU 14
2010/4/29 Mini-workshop on cosmic dust at IPMU 15
‘Stardust’ production
2010/4/29 Mini-workshop on cosmic dust at IPMU 16
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
2010/4/29 Mini-workshop on cosmic dust at IPMU 17
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
2010/4/29 Mini-workshop on cosmic dust at IPMU 18
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)
2010/4/29 Mini-workshop on cosmic dust at IPMU 19
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