Effects of early reionization oEffects of early reionization on the formation of galaxiesn the formation of galaxies

Hajime SusaRikkyo University

Impacts of UVB on GFImpacts of UVB on GFImpacts of UVB on GFImpacts of UVB on GF

PHOTO IONIZATION• Production of electrons : catalysts of H2

formation → enhance the fraction of H2

• Momentum Transfer PHOTO DISSOCOATION

• Dissociation of H2 → No coolant PHOTO HEATING

• Keep the gas temperature 104-105 K• Photo-evaporation• Suppression of SF in gals.

PHOTO IONIZATION• Production of electrons : catalysts of H2

formation → enhance the fraction of H2

• Momentum Transfer PHOTO DISSOCOATION

• Dissociation of H2 → No coolant PHOTO HEATING

• Keep the gas temperature 104-105 K• Photo-evaporation• Suppression of SF in gals.

Thoul & Weinberg 1996

Cooling and heating rates Cooling and heating rates Cooling and heating rates Cooling and heating rates

Equilibrium temperature is 104-105K

Dynamics of Galaxies with Tvir < 104 Kare strongly affected.

SF in cold HI phaseSF in cold HI phase---- Importance of RT and H---- Importance of RT and H22cooling ----cooling ----SF in cold HI phaseSF in cold HI phase---- Importance of RT and H---- Importance of RT and H22cooling ----cooling ----

Young & Lo 1996, 1997-1 -1Two phase HI : km s km s10 , 4 : :

• Leo A , Sag DIG : current SF, two phase• LGS 3 : no SF, no cold HI

They suggest that existence of cold HIphase is a good indicator of SF.

H2 cooling & Radiation Transfer

Cooling below 104 K and self-shielding against UVB

1.5 0.55

4 -310

10 1cmH

J

T nM M

K

¤

Runs in previous workRuns in previous workRuns in previous workRuns in previous work

15

8 9

2

1 9

10

SPH CDM

c

tot

N N

z

M M

¤

Initial Condition by GRAFIC in COSMICS

+ Rigid rotation with λ=0.05

Zreion ～ ７

Photo-evaporation → LG Photo-evaporation → LG dSph?dSph?Photo-evaporation → LG Photo-evaporation → LG dSph?dSph?

Dark dSphs have large M/L (Mateo 1998) 。→ evaporation of gas

Spheroidal system →merging of peaks

Most of the LG dwarfs have extended old population ( age > 10 Gyrs) (Mateo 1998) 。→ Cut-off of SFR

Dark dSphs have large M/L (Mateo 1998) 。→ evaporation of gas

Spheroidal system →merging of peaks

Most of the LG dwarfs have extended old population ( age > 10 Gyrs) (Mateo 1998) 。→ Cut-off of SFR

Early reionization (WMAP)Early reionization (WMAP)Early reionization (WMAP)Early reionization (WMAP)

( ) 0.17 0.04recz

Spergel et al. 2003

Instantaneous reionization:

17 3reionz

Substructure in Galactic HaloSubstructure in Galactic HaloSubstructure in Galactic HaloSubstructure in Galactic Halo

Moore et al. 1999Cluster Halo

Galactic Halo

M 145 10 8

M 122 10 820 times smaller than expected

Early Reionization, CDM density Early Reionization, CDM density perturbation, and Radiative cooling.....perturbation, and Radiative cooling.....Early Reionization, CDM density Early Reionization, CDM density perturbation, and Radiative cooling.....perturbation, and Radiative cooling.....

Blown away by photo-evaporation

7 20

ff coolt t

If Z_reion=7, 1σ density perturbations are not prevented from forming stars.

Early Reionization, CDM density Early Reionization, CDM density perturbation, and Radiative cooling.....perturbation, and Radiative cooling.....Early Reionization, CDM density Early Reionization, CDM density perturbation, and Radiative cooling.....perturbation, and Radiative cooling.....

Shaded Blown away ≒by photo-evaporation

7 20

Previous runs

This work ff coolt t

Method (RSPH)Method (RSPH)Method (RSPH)Method (RSPH) SPH

• Steinmetz & Muller 1993• Umemura 1993

Gravity• HMCS in University of Tsukuba (CCP)• GRAPE6, direct-sum

Radiation transfer of ionizing photons• Kessel-Dynet & Burkurt 2000 • Nakamoto, Umemura & Susa 2001

Primordial chemistry & Cooling• Susa & Kitayama 2000• Galli & Palla 1998

SPH • Steinmetz & Muller 1993• Umemura 1993

Gravity• HMCS in University of Tsukuba (CCP)• GRAPE6, direct-sum

Radiation transfer of ionizing photons• Kessel-Dynet & Burkurt 2000 • Nakamoto, Umemura & Susa 2001

Primordial chemistry & Cooling• Susa & Kitayama 2000• Galli & Palla 1998

Model of SFModel of SFModel of SFModel of SF

2

4

1 5000 K

3

2. 5 10

200

4 0

0 01 1

* **

.

.

.

, .gas

ff

H

T

d cc

dt t

y

v

Model of UVBModel of UVBModel of UVBModel of UVB

3

21 1 / 3 I z 　

1

21 exp 12 3 I z

1 z

21I

3 5

Put a source outside the simulation box so that the mean intensity is equal to above value at the center.

21 0.01 I

21 exp 3(17 ) I z

Early　Reionization　model

Evolution of IUV ：　 I211 at z=3, I210.1 at z=4, I210.01 at z=5

Determination of I21at high-z: Lyα Continuum Depression)( LyLy

Ly

Lycont

obscont

dD fff

A

Numerical simulations Confrontation with observationsNakamoto, Umemura & Susa (2001), Hiroi, Umemura Nakamoto in prep.

GP trough of High-z QSOsGP trough of High-z QSOsGP trough of High-z QSOsGP trough of High-z QSOs

Fan et al. 2002

21 120.67 0.013I d＠ z=6 、 α ＝５

Minimal IMinimal I2121Minimal IMinimal I2121

0.1, 1HIy

310 , 5HIy

310 , 1HIy

0.1, 5HIy

2

30

(1 )(1 ) 3

4L

plHIrec

HI L

hyI n z k

y

ResultsResultsResultsResults

Photo-evaporation works very well for z_c<15 and M<107M_sun.

For M ～ 108M_sun, the photo-evaporation redshift is as large as z_c=8-9

Photo-evaporation works very well for z_c<15 and M<107M_sun.

For M ～ 108M_sun, the photo-evaporation redshift is as large as z_c=8-9

SummarySummarySummarySummary

Formation of low mass galaxies are investigated by 3D RHD simulations with early reionization model.

We find zones of photo-evaporated galaxies and large M/L galaxies. But we need more simulations.

RT effect is important for the formation of large M/L galaxies

CDM substructure problem might be resolved solely by the early reionization model at dSph scale. But we need more detailed analysis.

We need statistical analysis in order to discuss the M/L peak of LG dSphs.

Formation of low mass galaxies are investigated by 3D RHD simulations with early reionization model.

We find zones of photo-evaporated galaxies and large M/L galaxies. But we need more simulations.

RT effect is important for the formation of large M/L galaxies

CDM substructure problem might be resolved solely by the early reionization model at dSph scale. But we need more detailed analysis.

We need statistical analysis in order to discuss the M/L peak of LG dSphs.