On the inside-out reionization of the MW satellite system

Transcription

1 On the inside-out reionization of the MW satellite system Reionization at galaxy-scale P. Ocvirk, D. Aubert Observatoire astronomique de Strasbourg Impact of radiation field structure on the Galaxy RT simulations, reionization history of the MW satellites Pierre OCVIRK - CRTCRPW - Austin 2012

2 MW Satellites LF Reionization & the Milky Way UV background => gas photo-evaporation Bootes D = 60 kpc rh = 220 pc Mv = -5.8 mag => suppression of low-mass galaxies => satellite galaxies, ultra-faint dwarfs Courtesy V. Belokurov and SDSS collaboration 100 zreion=5 Semi-analytical models N(<M v ) 10 zreion=12 Satellite SF stops at zreion => sats = reionization fossils z reion = 5 z reion = 8 z reion = 12 Busha et al reionization uniform & instantaneous M v

3 Impact of local structure of UV field at reionization on MW satellite pop UV cumulative normalized radial distribution of Milky Way satellites External, uniform BG Internal, inside-out SAM based on Via Lactea II photo-evaporation recipes from Iliev et al => Signature of reionisation geometry survives down to z=0 z=0 Simplification: unique central UV source -_- Ocvirk & Aubert 2011

4 Comparing with literature This work Koposov et al Maccio et al Munoz et al Busha et al Lunnan et al. 2011, self-consistent reionisation

5 Impact of local structure of UV field at reionization on MW satellite pop UV cumulative normalized radial distribution of Milky Way satellites External, uniform BG Internal, inside-out SAM based on Via Lactea II photo-evaporation recipes from Iliev et al => Signature of reionisation geometry survives down to z=0 z=0 Simplification: unique central UV source -_- Ocvirk & Aubert 2011

6 PICON PICON: Photo-Ionization of CONstrained realizations of the local group Radiative post-processing of high-res hydro simulation of local group formation HYDRO SIMULATION o CLUES 1 o Gottloeber et al o GADGET 2, WMAP3 (no live RT) o produces realistic MW+M31+M33 o Mpart= M (in HR region) RADIATIVE TRANSFER o ATON (Aubert & Teyssier 2008) o grid-based method o multi-gpu: CUDATON o Stellar sources T=50000 K, fesc=0.2 o H only chemistry, 1 photon group o ~20 h -1 kpc resolution, 512 3, 11 h-1 Mpc box 1 CLUES: Constrained Local UniversE Simulations Y. Hoffman (Racah Institute of Physics) G. Yepes (Universidad Autonoma de Madrid) S. Gottloeber (Leibnitz Institut fuer Astrophysik Potsdam) o No photo-evaporation/feedback!! o No external source (Virgo)

7 Post-processing of the CLUES simulation with ATON Setup geometry o Low res region => ρ=10-2 ρc o Box :11 h -1 o => ~20 h -1 kpc resolution MW Boundary conditions o Transmissive (photons get out) M31 o No external source (internal reionization) M33 <xneutral>ρ at z=9 11 h -1 Mpc

8 Local group reionization map MW o Slice through MW-M31-M33 plane 200kpc thickness o 2-4 major patches o patches more or less structured M31 o each galaxy reionizes in isolation o Is that always so? Ocvirk et al. 2012, submitted

9 Impact of source modelling Increasing emissivity Mt= M (halo detection limit) Tvir~10 4 K Mt~ M (z-dependent) Mt= M No feedback Lyman-Werner suppression of H2 formation (Shapiro et al.) Strong SN feedback (ref?) z (h Mpc) z (h Mpc) z (h Mpc) x (h Mpc) <z > x (h Mpc) <z > x (h Mpc) <z > running todo todo todo z (h Mpc) z (h Mpc) Increasing feedback strength x (h Mpc) <z > x (h Mpc) <z > zreion

10 Conclusions I MW o MW and M31 reionize in isolation except in the most extreme models (Strong SN feedback + high emissivity) o => modelling isolated MWs should be mostly ok in SAMs (cf Griffen et al. 2012) o low emissivity models => large Δzreion M31 o => effect on global satellite reionization history? o Effect of > 12.7 Gyr dynamical evolution?