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Kravtsov (U.Chicago) D. Ceverino (NMSU)

Galaxy Formation. 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). Hydrodynamic simulations of galaxies Rotation Curves and ISM of Dwarf Galaxies.

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Kravtsov (U.Chicago) D. Ceverino (NMSU)

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  1. Galaxy Formation • 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)

  2. Hydrodynamic simulations of galaxies • Rotation Curves and ISM of Dwarf Galaxies

  3. 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

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

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

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

  7. 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

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

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

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

  11. F.Governato: simulations with GASOLINE

  12. F.Governato: simulations with GASOLINE

  13. 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

  14. Credits: Kravtsov 100pc resolution Z=4 100 kpc scale Gas density 1 Mpc scale Tgas

  15. 350kpc Z=2.5 40pc resolution. Mvir(z=0)=1.e12Msun. Ndm=400K

  16. 350kpc Z=2.5

  17. 115kpc

  18. 7kpc

  19. 7kpc

  20. Isolated galaxies • Observations • Simulations

  21. Simon etal 04: NGC 4605 Vmax =100km/s -- Usual problems with NFW. -- Disk is important: normal M/LR=1 M/LK= 0.5 1arcmin

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

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

  24. Observations: • 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.

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

  26. Valenzuela et al 05 Code: GASOLINE Stars: phase-on Isolated Galaxy: NFW halo 1-2M particles Exponential disk 200K particles Gas 100K Resolution 50-100 pc Star formation, feedback …. Two simulations: dwarf: 60km/s M33-type: 120km/s

  27. YoungStars T<0.5Gyrs Hot Gas T=1e5 K Cold Gas T<1.5e4 Stars

  28. YoungStars T<0.5Gyrs Hot Gas T=1e5 K Cold Gas T<1.5e4 Stars

  29. Cold gas hardly shows any traces of the bar. • Filaments and lumps of cold gas • Large bubbles filled by 105K gas • Stellar feedback feeds the multiphase ISM

  30. Rotation Curves: Cold and Hot gas Little difference

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

  32. Recovering total density

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

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

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

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

  37. CONCLUSIONS • -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.

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

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

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