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A. Klypin (NMSU), D. Ceverino (NMSU/Jerusalem)

Physics of forming galaxies. A. Klypin (NMSU), D. Ceverino (NMSU/Jerusalem). 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).

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A. Klypin (NMSU), D. Ceverino (NMSU/Jerusalem)

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  1. Physics of forming galaxies A. Klypin (NMSU), D. Ceverino (NMSU/Jerusalem)

  2. 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

  3. 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

  4. 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!

  5. Governato, Mayer, Brook 2008

  6. Flat rotation curves are still the most sensitive test for feedback models Combination of resolution and feedback improves the rotation curves Ceverino & Klypin 2007 Resolution 45 pc. Thermal stellar feedback + runaway stars z=3.2 MW z=1 Dwarf Vcirc Vdm

  7. ISM and galaxy formation • Low efficiency of star formation: slow consumption rate • Turbulent ISM: rms velocity 1-10 kms • Molecular clouds are not spherical cows CfA: Heithausen & Thaddeus 1990 KOSMA: Bensch et al. 2001 IRAM: Falgarone et al. 1998

  8. ISM and galaxy formation • Efficiency of star formation: mass consumption • Efficiency of star formation: energy release • Angular momentum: flat rotation curves + thin stellar disks • Outflows: velocities, metallicites, QSO absorption lines

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

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

  11. Outflows: physics High velocities are not created inside the regions of star formation: rms velocity in molecular clouds is 1-10 km/s Young stellar cluster -> superbuble -> accelerated shock 4 kpc 10 pc

  12. Models of large-scale dynamics of ISM: 1pc resolution Pressure Density Temperature 100cm-3 107K 10-4cm-3 • Individual supernovae play very little role • Most of energy is lost in high density regions of star formation

  13. Gas Density 100cm-3 1cm-3 10-3cm-3

  14. 4 kpc. 12pc resolution Ceverino & Klypin 2007 Simulations of a Fragment of ISM Thin slices 1 kpc Plane of disk Orthogonal to the Disk plane

  15. Our implementation Ceverino & Klypin 2007 • Kravtsov ART hydro code: Physical processes included: • AMR shock capturing hydro • metallicity-dependent cooling + UV heating (Haardt & Madau). CLOUDY. Compton cooling • Temperature range for cooling: 102K -108K • Jeans length resolved with 4 cells • Energy release from stellar winds+ SNII +SNI • Thermal feedback: most * form at T< 1000K n>10cm-3 • Runaway stars: massive stars move with exp(-v/17km/s) Effective =150-1000 Myrs Mass consumption rate per free-fall time averaged over gas “molecular” gas (n>30cm-3) is 0.03 =2-20 Myrs

  16. Feedback: two conditions 1) Create overpressured region: Heating > Cooling Difficult to satisfy this condition for Tgas > 104K; need very lowgas density. Temperature regime 100-10000 K is crucial for initial stage of formation of superbubbles 2) Pressure gradient > gravity force: AntiJeans regime Limits on resolution: X < 70pc Need balance of force resolution X and threshold of star formation nH

  17. Modeling ISM: 12 pc resolution Early stages of evolution: first star cluster dumps its energy Wave accelerates on declining density

  18. 4 kpc Projection to the disk plane Projection along the disk plane Projected density Advanced stages: fully turbulent ISM

  19. 210 kpc Tasker & Bryan 2008: Isolated MW. 50 pc resolution

  20. Cosmology: formation of MW galaxy z=3.5 Major progenitor. 45 pc resolution Face-on view SFR =10Msun/year Ceverino & Klypin 2007 ART N-body+hydro code (Kravtsov) 400 kpc proper Cold Flow regime Slice of gas density

  21. Ceverino & Klypin 2007 z=3.5 Major progenitor of MW. 45 pc resolution Face-on view 400 kpc proper Cold Flow regime Slice of temperature

  22. Ceverino & Klypin 2007 z=3.5 Major progenitor of MW. 45 pc resolution Face-on view 400 kpc proper Cold Flow regime Vmax =1000km/s Slice of gas velocity: Log scale in km/s

  23. Ceverino & Klypin 2007 z=3.5 Major progenitor of MW. 45 pc resolution Face-on view 400 kpc proper Cold Flow regime Slice of gas density

  24. Ceverino & Klypin 2007 z=3.5 Major progenitor of MW. 45 pc resolution Face-on view 100 kpc proper Stars

  25. z=3.5 Major progenitor of MW. 45 pc resolution Face-on view Ceverino & Klypin 2007 100 kpc proper Gas velocity Log scale

  26. z=1.3 Major progenitor of MW. 45 pc resolution Face-on view

  27. z=1.3 Major progenitor of MW. 45 pc resolution Face-on view

  28. z=1.3 Major progenitor of MW. 45 pc resolution Face-on view

  29. z=1.3 Dwarf galaxy: Vmax =50km/s outflow= 2000 km/s Edge-on view 60 kpc

  30. Conclusions • Galactic Outflows are produced by forming galaxies: put it in right regime, it flies like a bird • Velocities: 300-500 km/s are typical at z=2-3. Large (1000-2000 km/s) outflows happen frequently. • Direction of outflows: • perpendicular to disk at small distances (10~kpc); • uncorrelated with disk at larger distances. Not random: outflows find holes in density field) • Small galaxies tend to have larger velocities given sufficient SFR (Dekel & Silk again) • Do not violate laws of physics simulating outflows. It is tempting, but do not do it. • Need to fulfill two conditions to have feedback efficient to produce out flows: • overheating regime • high resolution: better 50 pc • Mechanism for efficient feedback has important bottleneck: young stellar cluster => superbubble • Accelerating shocks • Two important tests for any design of feedback: • Flat rotation curves of galaxies (thin disks in spirals) • QSO absorption lines 31

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

  32. 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

  33. 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

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