EANAM2006( 大田 )

Radiation-SPH Simulations on the Radiative Feedback

of POPIII Stars

Hajime Susa (Rikkyo,JPN)Collaborator: Masayuki Umemura (Tsukuba)

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

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

EANAM2006( 大田 )

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

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>

EANAM2006( 大田 )

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)

EANAM2006( 大田 )

240 nodes

480 CPU ＋

240 Blade-GRAPE

480 Xeon : 2.9 Tflops

Blade-GRAPE: 8.7 Tflops

Memory: 　 512GB

　 FIRST 　

Now available

EANAM2006( 大田 )

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

EANAM2006( 大田 )

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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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

EANAM2006( 大田 )

Survived prestellar core (H2 fraction) 3 -3

on 10 cm

100pc

n

D

=

=H2 is self-shielded

Collapsed core

EANAM2006( 大田 )

Time evolution of Central density

collapse

bounce

Turn-on

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

EANAM2006( 大田 )

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)

EANAM2006( 大田 )

Comparison with the condition tdis > tff ( Glover & Brand 2001)

onn

onn

dis fft t

Importance of dynamical effect(H2 recovery)

EANAM2006( 大田 )

LW + Ionizing photonsSusa & Umemura (2006)Susa & Umumura in prep.

EANAM2006( 大田 )

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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Self-shielding condition for Static Core

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Disrupted Core by shock

M-type IF induce shock, that destroy the core.

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H2 shell formation&

Enhancement of H2 in the core

Bounce

1

310

610

910

310

pc10 pc20

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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

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