1 / 16 Numerical Simulations for Reionization of the Universe Nakamoto, T. (Univ. of Tsukuba) Hiroi, K. Umemura, M. 1. Why Reionization by 3-D RT ? 2. TsuCube Project 3. Tsukuba's New Code

2 / Why Reionization ? -Radiation Feedback ---- Effects for Following Generation - Photoionization - Photodissociation - Photo Heating -Observation ---- Probe for First Generation - Emissions - Absorptions

3 / 16 3D Reionization Calculations ・ Photon Conservation Method (+ Tree Method) Abel et al. 1999, Abel & Wandelt 2001, Razoumov et al ・ Optically Thin Variable Eddington Tensor Formalism Gnedin & Abel 2001 ・ Direct Incident Radiation Susa & Umemura ・ Monte Carlo 3D RT Ciardi et al. 2001, Maselli, Ferrara, & Ciardi 2003 ・ Grid Base 3D RT with Short Characteristics Nakamoto, Umemura, & Susa 2001 w/ HD w/o HD

4 / 16 N 3 ＝ in (8Mpc) 3, N angle = Radiative Transfer Ionization Equilibrium Isotropic background UV: I 21 =0.1 Zel’dovich approximation: z = 15 An Example: Evolution of Ionization State Nakamoto, Umemura, & Susa 2001 Neutral Fraction:

5 / 16 Shadowing Effect InhomogeneousHomogeneous

6 / 16 N 3 ＝ in (8Mpc) 3, N angle = Radiative Transfer Ionization Equilibrium Isotropic background UV: I 21 =0.1 Nakamoto, Umemura, & Susa 2001 Neutral Fraction: But... * Steady Solution (No Time Evolution) * Only Background Radiation (No Point Source) * Isothermal (No Temperature Evolution) * Only One Incident UV Spectrum ( I ν ∝ ν -1 )

7 / 16 We want to update our code! 1. Point Sources in Computational Domain 2. Time Evolution 3. Various Types Incident UV Spectrum 4. Temperature Evolution We can apply our new code to more problems!

8 / TsuCube Project Comparison of 3D RT codes Common Test Problems: Test #1, #2, #3 Groups/Codes: * CRASH (Ferrara, Ciardi, Maselli) * CORAL (Iliev) * OTVET (Gnedin, Abel) * Cen * Razoumov * Tsukuba (Nakamoto, Umemura, Hiroi) Deadline: January 31, 2004 (A. Ferrara, B. Ciardi...)

9 / 16 X e -R relation I-front propagation (Time Evolution) UV each grid point computation speed Test Problem 1: Input Output no dynamics

10 / 16 Test Problem 2: Input no dynamics (1,1,1) (128,128,128) non-isothermal (Temperature Change should be followed.)

11 / 16 Test Problem 3: Input no dynamics non-isothermal (Temperature Change should be followed.)

12 / 16 Tsukuba's New Code Ionization State Radiative Transfer Solver 1. Short Characteristics with point source(s) 2. ART (Accurate RT) Temperature Evolution Incident UV Spectrum * 3 (6)-frequency method * arbitrary spectrum Time Evolution * 2nd order implicit scheme new! * H, He 3. New Code

13 / 16 Point Source(s) in Computational Domain Radiation Energy Density Distance RT: Short Characteristics

14 / 16 Time Evolution 2nd order implicit scheme (Crank-Nicholson)

15 / 16 Spherically Sym. Solution by 1-D code J (Mean Intensity) X HI (Neutral Frac.) 10 8 yr 10 6 yr 10 4 yr [pc] R log J log X HI Time Evolution TsuCube Test #1

16 / Summary * Reionization Simulations * TsuCube Project: Comparison of 3D RT Codes * Developement of a New Code Point Sources Time Evolution of Ionization State Various Incident UV Spectra Temperature Evolution