Radiative Feedback on the formation of first generation subgalactic objects

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Radiative Feedback on the formation of first
generation subgalactic objects

• Hajime Susa
• Rikkyo University

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First Generation Objects

• Predicted by CDM density Perturbation Theory
  _at_10ltzlt30.
• Mgt106 M_sun (Tvirgt103 K)
• Cooled by H2 lines and H-Lya

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Cooling Diagram (RO H2)
3s
Cluster of Gals.
2s
1s
Large Gals.
dwarf Gals ?
First Generation Objs.
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3
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5
6
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8
9
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3
4
5
6
7
8
9
1
10
100
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Cooling by H atom
Cooling by H2
First Generation Subgalactic Objects
Nishi Susa 1999
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Substructure in Galactic Halo
Cluster Halo
Moore et al. 1999
Galactic Halo
20 times smaller than expected
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Feedback
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Cooling diagram of primordial gas SN disruption
100SN
Nishi Susa(1999)
Primodial Virialized Gas CoolingSN disruption
10SN
1SN
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SN (Simulation)
Wada Venkatesan 2003
z10, 108 M_sun
1000 SN/Myr ?disruption 100 SN/Myr ?collapse
induced
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SN feedback

• 108 M_sun halos _at_z10 seems to be difficult to
  be destroyed soley by SN.
• But more simulations are required to assess the
  effects of SN feedback

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Impacts of UVB on GF

• PHOTOIONIZATION
• Production of electrons catalysts of H2
  formation ? enhance the fraction of H2
• Enhance the Compton cooling rate
• PHOTODISSOCOATION
• Dissociation of H2 ? No coolant
• PHOTOHEATING
• Keep the gas temperature 104-105 K
• Photo-evaporation
• Suppression of SF in gals.

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Cooling and heating rates
Equilibrium temperature is 104-105K
Dynamics of Galaxies with Tvir lt 104 K are
strongly affected.
Photoevaporation
Thoul Weinberg 1996
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Late Reionization, CDM density perturbation, and
Radiative cooling.....
If Z_reion6, 1s density perturbations are not
prevented from forming stars.
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Early reionization (WMAP)
Spergel et al. 2003
Instantaneous reionization
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Early Reionization, CDM density perturbation, and
Radiative cooling.....
If Z_reion20, gt2s density perturbations are
prevented from forming stars.
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Smaller scale sub-clumps
In hierarchical clustering scenario, small
clumps evolve faster than the parent system.
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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

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Model of SF
In order to evaluate the case of maximal star
formation rate, we assume
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Model of UVB
Put a source outside the simulation box so that
the mean intensity is equal to above value at
the center.
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Minimally Required I21
??????
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Typical Result (M107Msun,Zc10)
300pc
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Maximally Star-forming model
3s
2s
Vc20 km/s
Evaporated
Vc10 km/s
1s
Vc5 km/s
gt95 halos are photo-evaporated.
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Convergence ( of particles and Softening )
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Substructure in Galactic Halo
Cluster Halo
Moore et al. 1999
Galactic Halo
20 times smaller than expected
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Kravtsov et al. (2004)
10 of halos with 108-109 M_sun halos are much
more massive in the past.
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Evidences of invisible substructuresby
gravitational lensing

• Chiba (2002)
• Dalal Kochanek (2002)

Consistent with the CDM N-body simulations
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Internal radiative feedback

• Kitayama, Yoshida, Susa, Umemura 2004
• single POPIII star at the center of the cloud

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?????
???????
??????????
????????????107 yr????????????
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?????????????

• ???First Stars ? Very Massive ?
• ????????T_virgt104 K ?????? ????
• ?????H2???????
• H2????????HD???????????????????????100Msun????????
  ??(F.Nakamura)?

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?????????
Susa et al. 1998
?????????? ???
???50km/s??? ?????????? ?a few 10-3??
?????? ???????????? ?????????
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Fragment mass
Nakamura Umemura 2002
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Summary

• 3D RHD ?????????????????????
• 20km/s??????????????????????????????????????
• ???POPIII????radiative feedback????????107Msun???
  ?????????????????
• ???????????????????????????104K??????????????????
  ???????????????????????????????????