原始銀河の進化と Lyman α Emitters
森正夫
筑波大学計算科学研究センター
筑波大学計算科学研究センター(2008年4月1日付けで専修大学から異動しました）(2008年4月1日付けで専修大学から異動しました）
2008年９月９日

初代星・銀河形成研究会＠甲南大学

Lyα emitters and Lyα blobs
Matsuda et al., AJ, 128, 569 (2004)

Extended LAEs

LAEs

Ouchi. et al. ApJS, 176, 3010 (2008)

Mass of Lyman alpha emitters

Lai et al., ApJ, 635, 704 (2007)

Low mass populations

108M~

Pirzkal et al. ApJ, 667, 49 (2007)

Mass of Lyman alpha blobs

1010M~

Uchimoto et al., PASJ, 60, 638 (2008)

Characteristics
Lya emitters
 Lya luminosity: 1042-43
 Size (Lya): a few kpc
 Morphology:
Lya: extended
UV: compact
 Stellar mass: 108-10 M~
 SFR: ~1-~10 M~ yr-1

Lya blobs
1042-44 erg/s
10-100 kpc
very extended
scattered~1010-11 M~~10-100 M ~ yr-1

Possible models of Lya emission
 Recombination
 Cooling radiation¾

Gravitationally heated gas in pre-galactic halo¾

Shock heating by supernova driven galactic windGalaxy formation and supernovaez

銀河全体の重力ポテンシャルエネル
ギー： Eg = E(M)
※NFW プロファイルを仮定

矮小銀河z¾¾¾¾¾¾

銀河内の全超新星によって発生する
熱エネルギー：
Et = E(M)※全質量の1%が短時間で星になったとした場合超新星の熱エネルギーが卓越
圧力勾配によりガスの流出
銀河風の発生大質量のガスの放出
星形成の抑止銀河形成が終わる星の超新熱ルギ
ネエ重エ
力力重ネエ

ギ
ルーールネ

ー
ギ

通常銀河

銀河の総質量銀河の総質量 M
M

Negative Effect: 輻射輸送による熱エネルギーの散逸？
Positive Effect: 超新星によって放出されたガスから星形成？

現実的な数値シミュレーション

3D hydrodynamics model
We consider a forming galaxy undergoing
multitudinous supernova explosions as a possiblemodel of Lymanα emitters.
To verify this model, a high-resolution hydrodynamic
simulation is performed using 10243 grid points, where
supernova remnants are resolved with sufficientaccuracy.
Numerical simulation:
 Three-dimensional hydrodynamics
 Gravity of dark matter halos (fixed potential)
 Radiative cooling (including H2 molecule and metals)
 Star formation
 Supernova feedback (thermal energy and metals)

Spectral Energy Distribution
Emission from stars
Population synthesis model: Fioc 1997 (PÉGASE)

Emission from gas
Collisional ionization equilibrium: Sutherland & Dopita 1993
(MAPPING III)¾¾¾¾

Bound-bound emission
Free-bound emission
Free-free emissionTwo-photon emission

Dust extinction
E(B-V)=(N/9.2x1021 cm-2) x10 [Fe/H]
Extinction curve: <Aλ/AB>Pei 1992

M=108 M~

Mori, Ferrara & Madau, ApJ, 571, 49 (2002)

M=1011M ~Total Mass:1011 M~
Gas Mass: 1.3×1010 M~
No. of Subunits: 20
Box Size: 134 kpc
Grid Points: 10243

log n (cm-3)-40

Mori & Umemura, Nature, 440, 640 (2006)

SED : Gas and Stars

stargasThe red (blue) lines indicate the emission from gas (stellar) component.
The absolute luminosities of Lymanα line emission are 2.0×1043 erg s-1, 1.6×1043 erg s-1, 4.6×1041 erg s-1, and 2.3×1041 erg s-1 at the elapsed timeof 0.1 Gyr, 0.3 Gyr, 0.5 Gyr, and 1 Gyr
In the first 0.3 Gyr, the luminosities completely match the observed Lyαluminosities of Lyαemitters.

Real vs Virtual

SED : Gas and Stars

After 300 Myr, the Lyα luminosity declines to less than the observed level. Then, the SED becomesdominated by stellar continuum emission.
The galaxy in this phase is featured with diffuse, asymmetric structures, and outflows of 100~500 km s-1.
The total stellar mass is 9.3×109 M~, and the mass of 1.5×109 M~ is involved in the outflows at z=3.
The X-ray luminosity changes from 1042 erg s-1 at 300 Myr to ~1041 erg s-1 around 1 Gyr.
These features look quite similar to those observed for Lyman Break Galaxies.

Evolution of Lyα emission andstellar continuum emission

Lyα+abs.
Lyα
UV cont.

LLy α > LUV
LAE phase

L Ly α < LUV
LBG phase

The results of our simulation indicate the possible link among LAEs and LBGs.
The simulated post-starburst galaxy with the age of 1 Gyr can correspond to LBGs.
It is implied that LBGs are the subsequent phase of LAEs.

 宇宙論的シミュレーション
 物理的シミュレーション¾¾

マイナーマージャーモデル
Mori & Umemura (2006)
シングルコラプスモデル
Fixed potential of Dark matter halo
Constant gas density
Rigid rotation λ = 0.05

Model and parameters







Total mass : 108-12 M , Total gas mass: 1.3x107-11 MΩM=0.3, ΩΛ=0.7, h=0.7, z=7.8, Ωb=0.024 h-2
Dark Matter: Navarro-Frenk-White densityGas: Constant density
Star formation :τcool < τff < τcros
3σ-3ρcrit=0.1 cmdρ* / dt = ρg / τff
2σSalpeter’s IMF
Supernova feedback:
ESN = 1051 erg / SN
1σ
Oxygen : 2.4 M / SNlog n16.4 Myr

35.9 Myr

59.8 Myr

[O/H]

log T

6.2 Myr

Mtotal=108 M~ , zcol=10.3

log n0.396 Gyr

0.580 Gyr1.21 Gyr[O/H]log T0.238 Gyr

Mtotal=1011 M~ , zcol=6.23

log n0.548 Gyr

0.723 Gyr

0.936 Gyr[O/H]log T0.351 Gyr

Mtotal=1012 M~ , zcol=2.98

Evolution of stellar component
Star formation rate

Stellar mass

Evolution of gas component
Gas mass

Energy carrying

Mass carrying

Mean metallicity

Filling factor
Metal freeZ > 0.001 Z~

Z > Z~

Z > 0.1 Z~Lyman alpha emission
Gas cooling radiation

1012

108

1011

109

1010

Stellar origin (HII)

SFR= 9.1x10-43 Llya
(Kennicutt 1998)

Origin of Lyman alpha photon
1010 M~

1011 M~

1012 M~

Red: cooling, blue: stellarSummary
We simulated a forming galaxy using a high resolutionhydrodynamic simulation, where supernova remnants areresolved with sufficient accuracy.
We have suggested that Lymanα emitters can be identified
with primordial galaxies catched in a supernova-dominatedphase.
The bubbly structures produced by multiple supernova
explosions are quite similar to the observed features inLymanα surface brightness of Lyman α blobs.
The resultant Lyα luminosity can account for the observed
luminosity of Lymanα emitters.
After 1 billion years the simulated galaxy is dominated bystellar continuum radiation and looks like the Lyman breakgalaxies. At this stage, the metal abundance reaches
already the level of solar abundance.