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EXPLOSION OF VERY MASSIVE STARS AND THE

ORIGIN OF INTERMEDIATE MASS BLACK HOLES

S. Tsuruta, T. Ohkubo, H. Umeda, K. Maeda, K. Nomoto, T. Suzuki, and M.J. Rees

IAU Symposium 238, Prague. Czech, August 24, 2006

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CONTENT

I. INTRODUCTION

II. OUR RECENT RESEARCH

III. SUMMARY/CONCLUSION

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Supernovae and Chemical evolution of the universeBig Bang

core-collapse SNe (massive)

type Ia SNe (light)

O,Mg,Si,Ca

only H, He (metal-free)

Mn,Fe,Co,Ni

present Sun Earth

Metal?

metal-rich universe

First Stars?

Metal1.37x1010

years

I. INTRODUCTION

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Final fate very-massive stars

Pair-Instability Supernova

Core-collapse

8 140 300 105

White Dwarf(SN Ia)

Core-collapse(SN II/Ib/Ic)

Relativistic instability(super-massive star)

stellar mass MUmeda & Nomoto 02Heger & Woosley 02

Our target

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Formation of Very-Massive Stars 　First generation stars

very-massive (over 300M) ?

cloud

proto star core

Radiation pressure is small in zero-metal environment

Proto star core can grow larger

Rees, Madau, in this symposium

Omukai & Palla 2003; Abel et al. 2002;

Tan & McKee 2004; Bromm & Loeb 2004;

Ohkubo et al. 2006, in preparation

Halo, dark matter and gas accretion

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Explosion of very-massive starsDoes a core-collapse very-massive star (M>

300M) explode?

black holeBut if it rotates

it may make a jet like explosion (GRB?)it may contribute to early chemical evolution

BHAccretion diskJet

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Intermediate Mass Black Hole

Stellar mass BH (~10 M ) IMBH Super-massive BH

(>106 M )

(IMBH, ~102 – 105 M) 　

Possible support: (1) ULX in M82 > ~ 700 M, etc., see Makishima, Mushotzky in this symposium

(2) Galactic Center: see, e.g., Genzel, etc., in this symposium

(3) Smallest Black Holes in AGNs:IMBH may be found by search of smallest black holes throguh AGN survey, using the

relation between the host galaxy and central black hole, – e.g., the extention of the σ-black hole mass relation for SMBH to lowest masses (small Seyferts, dwarf galaxies, etc.)

See, e.g., Barth et al. in this symposium

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Origin/Formation of IMBHThere are many possible ways

(A) If very-massive stars exist

they may be the origin of IMBH !! This talk, Ohkubo et al. 2006

(B) Intermediate stages from seed BH to SMBHSee, e.g., Rees, in this symposium

Black hole

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(C) Direct Collapse, from haloSee, e.g., Begelman, et al. 2006

(D) Successive merger of stars in a dense cluster: e.g., Portegies et al. 2004

Very-massive star (M>300M)

IMBH

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II. OUR RECENT RESEARCHOhkubo et al. ApJ, 645, 1352, July 10, 2006

Evolution

Explosion

Nucleosynthesis

zero-age main sequence to Fe-core collapse

(initial model for explosion, UV photon supply)

hydrodynamical calculation

2 dimensional jet like explosion

comparison with observational abundance pattern

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Evolusionary track ce

ntra

l tem

ope

ratu

re

central density

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ExplosionExplosion

dEjet/dt = (dMacc/dt) c2

jet: jet angle(15o)

initial BH mass…100M

: energy transformation efficiency 　　 (0.002 – 0.01)

1000M model (our result of evolution)Code ･･･ 2D hydrodynamical code including gravity (Maeda & Nomoto 2003) explosion energy source ･･･ jet injection around BH

BHJetDisk

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Snapshot of explosion 　 (density structure)

5sec 10sec

50sec 100sec

R/R

*

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Abundance pattern and comparison with observational data

Compare Abundance Pattern by nucleosynthesis with observational data

(extremely metal-poor stars, M82 gas, intracluster matter, inter galactic medium)

black hole mass increases by accretion

final black hole mass?

①

(very-massive star formation)Link ?

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　 Presupernova Composition

p

He

Fe

Si O

Ne

C

Mg56Ni

‘Fe’

p

He

1000M

For 25M Model, Fe-core is < 10%

(Umeda & Nomoto 2003)

Fe-core is >20%

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Abundance Patternε=0.0025; jet=15o

Metal-poor stars ([Fe/H]< - 3) (Cayrel et al. 2004)

there is discrepancy in [O/Fe]

[O/Fe] < 0 ,[Si/Fe] >0 : Consistent

EMP (extremely metal-poor) stars

ICM (intracluster matter)ε=0.005; jet=15o

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M82 hot gas

Gas composition in M82

(Origlia et al. 2004)

[O/Fe]~ - 0.3

[Ne/Fe]~0, [Mg/Fe]~ 0.3, [Si/Fe]~ 0.2

Black hole mass 500M 　… consistent with IMBH mass

　　 25M hypernova model

　　　　　　 Umeda & Nomoto (2002)

Consistent rather than 25M hypernova model

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• IGM (inter galactic medium) (redshift z:2~4.5)

• Observation: [C/Si] <~ - 0.5 (Aguirre et al. 2004)

• Yields by PISNe: [C/Si] ~ - 2.0 to - 1.7• Our 1000M yields: [C/Si] ~ - 0.78 to - 0.65

Consistent in order of magnitude with observational ratio

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UV photon supplyLog(Teff) ~ 　 5.05 (4.85 – 5.0 for Pop III 15 – 90M stars)

(Tumlinson & Shull 2000)

　　　　　 Ionizing photons (/s/M)

H I : 1.6 × 1048 (16 times higher)

He I : 1.1 × 1048 (14 times higher) He II: 3.8× 1047 (75 times higher ) than by Salpeter IMF (values with a Salpeter IMF)

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UV photon supply and chemical contamination

• Nreionize / Nb (Number of UV photon supply per baryon) 　 ~150

( >> 10…necessary for reionization of IGM at z~4 )Miralda-Escude&Rees 97

UV photon supplyevolving stars

exploding star chemical contamination

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This work

normal SN

Hypernova

PISN

this work

Initial Mass

Ene

rgy

(erg

)

10 100 1000

1051

1052

1053

1054

1055

1056

300

1000M model…core-collapse very-massive stars

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III. Summary/CONCLUSION

(i) 1000M stars …UV photons efficiently supplied 　

(ii) Final black hole is ~ 500M

…consistent with IMBH mass

(iii) Abundance pattern

…consistent with M82 gas, ICM, IGM