2. A.Kravtsov (U.Chicago) D. Ceverino (NMSU) O. Valenzuela (U.Washington) G. Rhee (UNLV) F. Governato, T.Quinn, G.Stinson (U.Washington) J.Wadsley (McMaster, Canada) Galaxy Formation

3. Hydrodynamic simulations of galaxies Rotation Curves and ISM of Dwarf Galaxies

4. Numerical simulations : recent progress Stellar Disk and Bulge: is there a thin disk? Is bulge too massive? Angular momentum Tully-Fisher relation Feedback How gas gets to the disk? Mbaryons/Mhalo ratio

5. Robertson et al. 2004 Abadi et al 2003 Hydrodynamical simulations of galaxy formation in a cosmological context. (50.000 DM particles) (40.000 DM particles) gasstars

6. A LCDM galaxy at z=0 Governato et al 04 Age > 10 Gyr Age < 10 Gyr Only Stars are shown (brighter colors for younger ages) boxes 40 kpc across Disk Bulge + Stellar Halo N>100.000

7. Increasing Resolution Conserves Angular Momentum in Disks 4000 DM 10.000 DM 100.000 DM If DM+stellar component not collisionless: Massive halo particles exchange E and J with disk particles ---> disks heat and lose angular momentum

8. Angular momentum of Stellar Disks increases with resolution. Galaxies still too concentrated Abadi et al. 2003 Governato et al. 2004 (see also Robertson 05 Okamoto 05) stars

9. High Spin Halo (0.05) Vc =170Km/sec Low Spin Halo (0.01) Vc =70Km/sec Due to sufficient resolution 300pc disks form with the right angular momentum Credits: Governato

10. 8 10^11 solar masses3 10^12 solar masses Galaxies too concentrated. B/D 1:3 or higher. Peak velocity higher than in the real Milky Way. No realistic feedback yet! Governato et al. 04 Abadi et al 03 Governato

11. The Feedback and satellites : No Feedback.UV+SN Feedback Red: stars Blue: gas Total Mass 3e12 Msol Spin Parameter = 0.035 Vrot Max 270 Km/sec Formation time z = 0.75 Last major merger z=3 Frame size ~ 200 Kpc

12. 12 F.Governato: simulations with GASOLINE

13. 13

14. 14 F.Governato : simulations with GASOLINE

15. How gas gets to the disk The old picture is wrong: do not even think about spherical accretion and shocking to virial temperature Still not clear what fraction of gas comes with satellites and what comes with filaments

16. 1 Mpc scale 100 kpc scale T gas Gas density Credits: Kravtsov 100pc resolution Z=4

17. 350kpc Z=2.5 40pc resolution. Mvir(z=0)=1.e12Msun. Ndm=400K

18. 350kpc Z=2.5

19. 115kpc

20. 7kpc

23. Isolated galaxies Observations Simulations

24. Simon etal 04: NGC 4605 Vmax =100km/s -- Usual problems with NFW. -- Disk is important: normal M/L R =1 M/L K = 0.5 1arcmin

25. Simon etal 04 NGC 4605 POSS II Changes in PA and inclination in central 1kpc are consistent with a weak bar

26. DDO 47: Vmax = 80km/s Distance = 4Mpc HI is very lumpy Stellar light does not align with HI

27. A large fraction of dwarf Galaxies in the central 1kpc has a maximal disk with expected stellar population (judging by colors). Signs of a weak bar are frequent. ISM is very clumpy. Observations:

28. LMC HI distribution Venn+Stavely Smith 2003) Cosmological Simulations: feeback, 300pc resolution … Governato 2004 Multiphase ISM is nicely reproduced

29. Valenzuela et al 05 Isolated Galaxy: NFW halo1-2M particles Exponential disk 200K particles Gas100K Resolution50-100 pc Star formation, feedback …. Stars: phase-on Two simulations: dwarf: 60km/s M33-type: 120km/s Code: GASOLINE

30. Stars Young Stars T<0.5G yrs Cold Gas T<1.5e4 Hot Gas T=1e5 K

31. Cold Gas T<1.5e4 Hot Gas T=1e5 K Stars Young Stars T<0.5G yrs

32. Cold gas hardly shows any traces of the bar. Filaments and lumps of cold gas Large bubbles filled by 10 5 K gas Stellar feedback feeds the multiphase ISM

33. Rotation Curves: Cold and Hot gas Little difference

34. Gas Rotation Circular Velocity Asymmetric drift (aka random motions) cannot help to explain why gas rotates too slow Rms Velocities < 20km/s

35. Recovering total density

36. Another simulation: dwarf 5 Resolution: 60pc stars Cold gas dm baryons Gas rms velocity Valenzuela, Rhee, Klypin, Governato et al. 2005 Models of NGC3109 and NGC6822

37. Cold Gas density in the central 2kpc region: Clear signs of multiphase medium

38. Cold/Hot Gas: density Stars Cold Gas:velocity

39. NGC 6822 Observations Vcirc(total) Magellanic-type dwarf irregular 0.5Mpc from Milky Way

40. -In dwarf galaxies gas does not rotates fast enough: Vgas < Vcirc -Non-circular velocities are not large enough to account for the difference -Pressure support from 1e5K gas is one of key ingredients Core is ‘observed’ where there is a real cusp. CONCLUSIONS

41. Structure of the ISM at z= 0.5 ( several 10^6 particles per halo, gas clouds resolved down to 10^5 solar masses ) Ram Pressure Stripping Cold Gas in Disks High Velocity Clouds Gas Rich Satellites Hot Halo (Blue)

42. Bars in galaxies: Simulations with ART and Gadget. 50-100pc resolution 200K disk particles 2M dm particles. Dt =1e4 yrs