1. Andrey Kravtsov Kavli Institute for Cosmological Physics (KICP) The University of Chicago Simulating galaxy formation at high redshifts

2. The sexiest simulation? http://www.this-wonderful-life.com

3. SDSS survey By Mark SubbaRao (Adler/U.Chicago) Dinoj Surendran, and Randy Landsberg (U.Chicago) http://astro.uchicago.edu/cosmus/ The ultimate simulation should be able to simulate this…

4. While resolving this SDSS survey By David Hogg and Michael Blanton (NYU)

5. Simulations are remarkably successful in reproducing the observed LSS ART code: LCDM 60 h -1 Mpc  8 =0.9; m p =10 9 h -1 Msun;  = 0.5h -1 kpc

6. n(>V max,acc )=n(>L) Conroy, Wechsler & Kravtsov (astro-ph/0512234) Conroy, Wechsler & Kravtsov (astro-ph/0512234) projected 2-point correlation function projected separation (chimps) Galaxy clustering in SDSS at z~0 Is well reproduced by simulations

7. n(>V max,acc )=n(>L) Conroy, Wechsler & Kravtsov (astro-ph/0512234) Conroy, Wechsler & Kravtsov (astro-ph/0512234) projected 2-point correlation function projected separation (chimps) and at z~1 (DEEP2)

8. n(>V max,acc )=n(>L) Conroy, Wechsler & Kravtsov (astro-ph/0512234) Conroy, Wechsler & Kravtsov (astro-ph/0512234) angular 2-point correlation function projected separation (arcsec/chimps) and at z~4-5 (LBGs, Subaru)

9. CDM paradigm must also be tested on smaller, galactic scales

10. It’s a very difficult problem

11. (some of) the reasons:  resolution and dynamic range required to simulate internal structure of galaxies, star formation, and feedback properly is enormous: I would argue, we won’t get very far until resolution element in star formation regions is ~10 pc (i.e., ~10 6 dynamic range in a box of 10 Mpc). The scale-height of star forming gas disk in the MW is ~100 pc. Bar formation and dynamics requires ~10 pc resolution and millions of stellar particles to resolve the relevant orbital resonances properly.  currently, such dynamic range is achievable only at high redshifts  high-z’s also are less complicated in certain physical aspects (e.g., low dust content)

12. Gasdynamics+DM simulations of a MW-size system Adaptive Refinement Tree (ART) code Eulerian Adaptive Mesh Refinement hydrodynamics N-body dynamics of DM and stellar particles radiative cooling and heating: Compton, UV background heating, density and metallicity dependent net cooling/heating equilibrium rates taking into account line and molecular processes Star formation using a phenomenological recipe Thermal stellar feedback and metal enrichment by SNII/Ia, stellar mass loss Simulation followed formation of a MW-size galaxy at z > 3. A Lagrangian region corresponding to 5 Rvir of the object at z=0 was followed. Peak resolution in this region was ~50 pc particle mass ~10 6 Msun

13. Milky Way progenitor at z=4 Kravtsov 2003; Kravtsov & Gnedin 2005 Kravtsov 2003; Kravtsov & Gnedin 2005

14. Density PDF and SF Kravtsov 2003 Kravtsov 2003

15. Stellar cluster mass function Kravtsov & Gnedin 2005 Kravtsov & Gnedin 2005

16. Stellar cluster mass function in Antennae

17. Exploring dependence on physics: non-equilibrium cooling and radiative transfer visualization with IFRIT (http://home.fnal.gov/~gnedin/IFRIT/) visualization with IFRIT (http://home.fnal.gov/~gnedin/IFRIT/)

18. Dwarf galaxies at z~8 Ricotti & Gnedin 2005 Ricotti & Gnedin 2005

19. Dwarf galaxies at high z Show correlations observed locally M/L – metallicity correlation M/L – metallicity correlation

20. Dwarf galaxies at high z Show correlations observed locally metallicity-stellar mass correlation metallicity-stellar mass correlation

21. Dwarf galaxies at high z Show correlations observed locally surface brightness-stellar mass correlation surface brightness-stellar mass correlation

22. Formation of a Milky Way-sized halo ART code simulation (by Anatoly Klypin): standard LCDM,  8=0.9; mp=6x10 5 h -1 Msun;  = 0.1h -1 kpc Mvir=3x10 12 h -1 Msun; Rvir=293h -1 kpc; ~5x10 6 particles within Rvir time z = 10z = 7z = 5z = 3 z = 2z = 1z = 0.5z = 0

23. Survival probability for objects at z~8

24. Luminosity function of dwarfs in the Local Group

25. Conclusions  simulations of galaxy formation at high z have a number of advantages  we can learn more about galaxy formation physics, with (arguably) fewer uncertainties in the modeling  results are relevant for local observations of galaxies: star formation law, stellar clusters, dwarf galaxies