Radiation-SPH Simulations on the Radiative Feedback of POPIII Stars
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EANAM2006( 大田 )
Radiation-SPH Simulations on the Radiative Feedback
of POPIII Stars
Hajime Susa (Rikkyo,JPN)Collaborator: Masayuki Umemura (Tsukuba)
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EANAM2006( 大田 )
Radiative Feedback
• Processes– photoionization
• photoevaporation • enhance H2 formation
– H2 dissociation by Lyman-Werner (LW) Band photons• H2 destruction • H2+, H- destruction
• Outcome– self-regulation of SF in the early universe– Source of reionization
Abel et al. 2006
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EANAM2006( 大田 )
Three phases of Radiative feedbackfrom dark to luminous ages
• Phase I: local feedback from single POPIII ( ionization+dissociation )
e.g. Omukai & Nishi 1999; Glover & Brand 2001; Susa & Umemura 2006; Ahn & Shapiro 2006; Yoshida et al.(2006)
• Phase II: diffuse LW background (built up by many stars)
e.g. Haiman et al. 1997; Ciardi et al. 2000; Oh & Haiman 2003 ; Mesinger ,Bryan, Haiman 2006
• PhaseIII: diffuse ionizing photon background →Reionization of the univ.
e.g. Barkana & Loeb 2000; Kitayama et al. 2000,2001; Susa & Umemrua 2004ab
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2
3/ 4
,0 14 -210 cmH
LW LWN
L L-æ ö÷ç= ÷ç ÷çè ø
( )2
126 2
20.88 10 ( )4LW
H eL
n x Tnrp
--= ´ equi l i bri um
( ) ( ) ( )11 23,03 3
4 24 -1 -1 3 -31kpc10 10 ergs Hz 10 K 1cm
LWesh
Lx T nr
-- -
-
æ ö÷ç ÷ç= ÷ç ÷ç ÷ç ÷è ø
Local H2 photodissociation feedback in uniform gas cloud
Uniform low mass host clouds are totally Photodissociated by single POPIII star.
Omukai & Nishi 1999
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EANAM2006( 大田 )
H2 photodissociation feedback on clumpy cloud
• Dynamically collapsing cloud ?• Photoionization?
Glover & Brand 2001
3 -3crit 100pc@ 10 cmclumpD n »;
Dense clouds are able to survive the photodissociation feedback by another nearby star. dis fft t<
dis fft t>
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Numerical Methods
• Tree
• SPH
• RT of Ionizing photons by Ray Tracing
• RT of Lyman-Werner photons by Ray Tracing ( Self-Shielding function)
• Implicit solver for reactions and energy equation
• H2 (no He)
• Everything parallelized utilizing MPI
( ) 2
2 2
3/ 414 2
14 2 if 1010
HLW sh H H
NF f N N cm
cm
--
-
æ ö÷çµ = >÷ç ÷çè ø
H. Susa, PASJ 58, 445 (2006)
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240 nodes
480 CPU +
240 Blade-GRAPE
480 Xeon : 2.9 Tflops
Blade-GRAPE: 8.7 Tflops
Memory: 512GB
FIRST
Now available
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Setup
SPH particlesUniformly Distributed
48.3 10 M´ ¤3
clump 10cmn -=
3env 0.1cmn -=Uniform
dense clump
Run-away collapsing Core
pcD
(center)H onn n>
Turn on the nearby star
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Parameters
2 5 310 10 cmonn -= :
524288SPHN =
Property of the Source Star
120M¤49.92 10 K´4.6R¤
10pc 150pcD = - c.f. size of the first star forminghalos are several ×10pc
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EANAM2006( 大田 )
LW feedback (without ionization)
Susa 2006 in prep.
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Failed Collapse ( H2 fraction )3 -3
on 10 cm
40pc
n
D
=
= LW photons sweep the dense core and prevent the cloud from collapsing.
Core bounce
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Survived prestellar core (H2 fraction) 3 -3
on 10 cm
100pc
n
D
=
=H2 is self-shielded
Collapsed core
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Time evolution of Central density
collapse
bounce
Turn-on
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EANAM2006( 大田 )
Evolution of central density & tempetarute
collapse
Bounce
Thr
ee d
iffe
rent
init
ial T
of
coll
apsi
ng c
loudH2 reformation
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Analytic cooling condition
Once the collapsing core satisfy above condition, the collapse cannot be stopped.
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D=20pc
collapseBounce
RUN AWAY REGION
Susa, in preparation (2006)
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EANAM2006( 大田 )
Comparison with the condition tdis > tff ( Glover & Brand 2001)
onn
onn
dis fft t
Importance of dynamical effect(H2 recovery)
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LW + Ionizing photonsSusa & Umemura (2006)Susa & Umumura in prep.
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Photoevaporation (less dense core)
• All of the gas is photoevaorated andthe dense clump disappers
• The I-front propagates as R-type.
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EANAM2006( 大田 )
Self-shielding condition for Static Core
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EANAM2006( 大田 )
Disrupted Core by shock
M-type IF induce shock, that destroy the core.
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EANAM2006( 大田 )
H2 shell formation&
Enhancement of H2 in the core
Bounce
1
310
610
910
310
pc10 pc20
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EANAM2006( 大田 )
Competition of various effects
• H2 dissociation
• Photoevaporation (thermal pressure / shock)
• Self-shielding (LW / ionizing photons)
• Enhanced H2 formation in the core (→Ahn)
• H2 shell formation
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EANAM2006( 大田 )
Summary of Runs (non-D plane)
onn
onn onn
Effects of photoionization alleviates the negative feedback of photodissociation
LW only LW + ION dis fft tdis fft t