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2012 - - PowerPoint PPT Presentation

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2012 / IPMU Contents Early universe simulations The primordial IMF Technical challenges and

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初代星•初代銀河 形成シミュレーション

吉田直紀 東大 理物理/カブリIPMU

理論懇 2012 計算宇宙物理学の新展開

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Contents

✦ Early universe simulations ✦ The primordial IMF ✦ Technical challenges and the future

References & collaborators: Bromm & NY, 2011, Annual Review of Astronomy & Astrophysics Greif, Bromm, Clark, Glover, Klessen, NY, Springel, 2012, MN Smith, Iocco, Glover, Schleicher, Klessen, Hirano, NY, 2012, ApJ Naoz, NY, Gnedin 2011, ApJ Naoz, NY, Gnedin 2013, ApJ in press Hosokawa, NY, Omukai, Yorke, 2011 Science; 2012 ApJL Hirano & NY 2013, ApJ in press Chiaki, Nozawa, NY, in preparation Hirano, Hosokwa et al in preparation

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Most distant galaxy

z ~ 9.6 t~500 Myrs 星形成効率 電離光放出•脱出率

(大内講演）

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Stellar relics in the MW

A forbidden star Low-mass (<1Msun), extremely metal-poor (not only iron-poor) Z < 4.5 x 10-5 Zsun

Caffau et al. 2012

(千秋ポスター参照)

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Theory

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STANDARD COSMOLOGICAL MODEL THEORY OF STAR FORMATION molecular cloud protostar star

4% 22% 74%

inflation dark matter early structure

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Putting the early universe on a computer

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chemistry radiation cosmology dark matter “Egli è scritto in lingua matematica”

  • Galileo Galilei
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Gravity: dark matter web

2 trillion-particles resolution (石山講演)

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Hydrodynamics

An example of a moving mesh sim (Greif+11)

(+輻射圧)

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Chemistry

+ ~50反応式 (>100 if with C, O etc)

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Radiative transfer

分子線輸送と高密度領域でのエネルギーロス H2-He, H2-H2, H2-H 衝突による赤外光放出

密度、温度、分子率、形状の関数 ~200 レベル遷移

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Structure of a disk: with/without radiative transfer 3D effect important in post-collapse simulations 3D cooling efficiency

line continuum

Hirano & NY, 2013, ApJ

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Supersonic stream

Tseliakhovich & Hirata 2011; Visbal+ 12; Naoz, NY, Gnedin 11,12

Relative motions between gas and dark matter

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Multi-component ICs

NY, Sugiyama, Hernquist 2003, MN

Perturbation evolution: theory vs simulations

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Effect on early structure

Gas fraction

Naoz, NY, Gnedin 2011;2013

Filtering mass prescription

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Pre-collapse phase

1AU 1solar radius density velocity The mass of the new-born protostar ~ 0.01 Msun Dark matter plays little role after run-away collapse (unless DM annihilates)

Inside-out, in a self-similar fashion

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Post-collapse phase

Greif, Bromm, Clark, Glover, Smith, Klessen, NY, Springel, 2012

Early evolution of the proto-stellar disk

Small fragments are merged onto the central protostar on an

  • rbital time scale

“Gravo-viscous accretion”

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The Key Question How and when does a first star stop growing ?

明確な予言が必要

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Protostellar evolution to main-sequence

HII region break-out

Radiation-hydro. calculation (既 細川講演） Ionizing photon transfer by ray-tracing, continuum (H-) by Flux Limited Diffusion.

  • H. Yorke’s code

+ non-eq. chemistry. Initial condition taken from

  • ur cosmological run.
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Accretion vs evaporation

Accretion rate onto the protostar

Photo-dissociation Cloud evaporation

Final mass

Hosokawa, Omukai, NY, Yorke, 2011, Science

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Long standing puzzle resolved

Iwamoto et al. 2005 Abundance pattern from a 25 Msun Hypernova model

[Fe/H] < -5

Observed elemental abundances

Core-collapse SN models of 20-40 Msun progenitor

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Primordial IMF

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“Cosmic variance”

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“Cosmic variance”

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Toward Primordial IMF

  • S. Hirano+ in prep.

A sample of gas clouds

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  • S. Hirano+ in prep.

Mass distribution

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(計算物理的) Future

Dark matter: 0.1-1 trillion particles Gas : with refinements down to Rsun Chemistry : non-eq. ⇄ eq ⇄ non-eq. Radiative transfer: line (OK), infrared (FLD?), ionizing UV (ray-tracing) Protostar structure rotation, surface structure

現象として難しい部分が出てくるだろう

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Future development 1

Small-scale dynamo in action Adding weak B-field

Turk+12

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Future development 2

Hosokawa, NY, Omukai, Yorke, ApJL, 2011

Post III.1, e.g. III.2

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Chemo-Thermal Instability

Q gets larger than 1, but not much larger. Collapse is just ‘chemo- thermally’ accelerated. (NY, Omukai 06) Q=収縮時間/成長時間 d ∝ exp(wt) Perturbation analysis Needs to be revisited with extreme resolutions

個人的に気掛かりな事

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III.1 vs III.2

The initial accretion rate is smaller in III.2 (owing to HD cooling). KH contraction begins earlier, at a small stellar

  • mass. But ionizing

luminosity increases quickly. → Growth halted early at M ~ 10 Msun

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Future development 3

Chiaki, NY, Kitayama, 2013

Early SN remnant with 10-5 Zsun Fragmentation of a cooling shell

Cooling by dust

Low-metallicity star formation → first galaxies

テキスト

HD cooling

SN remnant

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Yet another direction

Heating and disk fragmentation

Smith+12, ApJ

Supersymmetric dark matter

density

106 108 1010 1012 1014 1016

dark matter heating

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まとめ

  • 初代原始星進化•形成の全体を追えるように

なった (日本の力） 次の目標はfull 3D 珍しくcomputer power limited

  • 初代銀河のシミュレーションにはさらに複雑

な物理が必要 (重元素、ダスト、磁場、乱流） 最初の試みがなされつつある

  • TMT/JWST/SKA の時代には明確な理論予言

が必要（つまりあと10年）