1. Making a virtual Universe Adrian Jenkins - ICC, Durham University

2. Outline Introduction: Modelling a galaxy population Example of an application Hubble volume simulation Future projects: Millennium simulation

3. Introduction Galaxy formation Modelling galaxy populations

4. Galaxy Formation Cosmological model ( , , h) dark matter Formation and evolution of galaxies Primordial fluctuations  /  (M, t) N-body/gasdynamics simulations Semi-analytics (+N-body simulation) Dark matter halos

6. Halo Merger History John Helly

7. White & Rees ‘78 Fall & Efstathiou ‘80 Semi-analytic model of galaxy formation

8. Halo Merger History John Helly

9. Cooling onto a disk Halos merge Galaxies merge; if major merger, spheroid forms with starburst New disk may form by further cooling

10. Galaxies in a Virgo N-body simulation Observable properties of galaxies in each N- body halo computed using the SA model: colour  B-V; size ~ M b Galaxies trace filaments Red galaxies in clusters Benson, Frenk, Baugh, Cole & Lacey ‘01 Z = 0

11. 3000 Mpc/h ΛCDM Hubble Volume Simulation A virtual universe: Hubble volume simulations 2dF redshift survey

12. 2dF vs mocks from Hubble vol simulation

13. The 2dF galaxy power spectrum Galaxy power spectrum in redshift space, convolved with survey window, inclunding non-linear effects

14. Future Plans Millennium simulation: 10 billion particles

15. Data sizes: Each output -- 300 Gbytes To make merger histories need 50 outputs -- 15 Tbytes Post-processing will allow some reduction but not by a large factor Final product: a Virtual universe Galaxy population in 500 Mpc/h volume – complete to L* + 5 at all redshifts and wavelenghts Including spectrophotometric, structural and chemical and clustering properties of all the galaxies.

16. Conclusions The construction of virtual universes to aid the analysis of real data is becoming increasingly common. The required sizes of these kinds of datasets is becoming very large. The size of the collaborations that generate and utilise these kinds of data is growing larger.

17. Future Collaborations EC Framework 6 network - Virgo institutions + Paris, Padova, Warsaw, Talin, Harvard, Michigan, McMaster, Victoria DEISA - linking IBM SP4s in Europe including HPCx Virgo/EPCC/RZG

18. Virtual Universe

21. Example 2: 2dF galaxy groups