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Cosmological simulations Analytical model Model vs observations

The History of the Baryon Budget Yann Rasera Supervisor: Romain Teyssier and Jean-Pierre Chièze Horizon Project. Cosmological simulations Analytical model Model vs observations. Cosmological Simulations. RAMSES an Adaptative Mesh Refinement code Hydrodynamics and gravity

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Cosmological simulations Analytical model Model vs observations

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  1. The History of the Baryon BudgetYann Rasera Supervisor: Romain Teyssier and Jean-Pierre ChièzeHorizon Project • Cosmological simulations • Analytical model • Model vs observations Rencontres de Moriond

  2. Cosmological Simulations • RAMSES an Adaptative Mesh Refinement code • Hydrodynamics and gravity • Cooling: primordial abundances • Heating: Haardt&Madau (1996) UV ionizing background • Star formation: Schmidt law and comoving density threshold • Serie of simulations • One very high resolution run • 5123 coarse cells/5 refinement levelformal resolution 163843 !!! • 350h on 256 processors up to z=2.8 • Box length: 10 h-1 Mpc • Star formation time scale t*= 30 Gyr • 6 high resolution runs • 2563 coarse cells/5 refinement level formal resolution 81923 !!! • Box length: 1-10-100 h-1 Mpc • Star formation time scale t*= 3 and 30 Gyr Rencontres de Moriond

  3. Gas density (z=3) Rencontres de Moriond

  4. Stellar density and age (z=3) Rencontres de Moriond

  5. Results (z=3) Gas density 2500h-1kpc 630h-1kpc 160h-1kpc 40h-1kpc Age and density of stars Rencontres de Moriond

  6. Analytical model Goal: Fast prediction of the baryon budget history 4 BARYON PHASES: • Diffuse gas (Ly) • Hot gas in halos • Cold gas in discs • Stars Rencontres de Moriond

  7. A simple analytical model • Cosmic accretion rate: • Accretion of diffuse gas (Tvir>Tmin) • Cosmic cooling rate: • Fast cooling: • Slow cooling (Bremsstrahlung): • Average over the mass function: • Star formation and cosmic winds: • Star formation rate: • Winds: • 2 main physical parameters: and Rencontres de Moriond

  8. Evolution of the 4 phases • Ordinary differential equations Note: IDL routine avalaible upon request Rencontres de Moriond

  9. t*=2Gyr/w=3 t*=3Gyr t*=30Gyr 10h-1Mpc 3243 2163 1443 963 643 1h-1Mpc 100h-1Mpc RAMSES, no winds Rasera&Teyssier 2005 GADGET, with winds Springel&Hernquist 2003 Physical density threshold Comoving density threshold Validation of the model Good estimate of finite mass resolution Simulations vs analytical model Rencontres de Moriond

  10. Influence of the 2 main parameters t*=halo star formation time scale Delays CSFR w=wind efficiency Lowers CSFR Analytical model: fast parameter space exploration Rencontres de Moriond

  11. Observations vs model:SFR(z) Elbaz compilation: Hughes et al. 1998, Steidel et al. 1999, Flores et al. 1999, Glazebrook et al. 1999, Yan et al. 1999, Massarotti et al. 2001, Giavalisco et al. 2004 • Good fit: star formation time scale t* ≈ 1-5 Gyr winds w≈1-3 • Our favorite model (see later): t*=3Gyr/w=1.5 Rencontres de Moriond

  12. Comoving stellar density: Ω*(z) • Ω* for the same parameters • IMF: Kroupa  50% of stars dead at z=0 • z=0: Observed Ω* compatible with CSFR constraints • z=3: same models predicts 3 times more stars than observed!? Problems in the model? In CSFR? In Ω*? Rencontres de Moriond

  13. Extragalactic Background Light IEBL=80 nW/m2/sr from Bernstein et al. 1999, Chary&Elbaz 2001, Fixsen et al. 1998 • Bolometric luminosity from Madau&Pozzetti (2000) • Similar constraints than Ω*(z=0) • IEBL(t*=3Gyr, w=1.5)=100 nW/m2/sr Rencontres de Moriond

  14. Comoving cold gas density: Ωcold(z) • Damped Lyman Alpha: dust corrected by Pei et al. 1999 • Constraints on the gas consumption time scale: t*/(w+1)≈1Gyr • Good agreement with our favorite model Rencontres de Moriond

  15. Individual average SFH • Heavens et al 2004: stellar population of 100000 galaxies (SDSS) • Large galaxies form stars earlier than small one • Fast decline of SFH for large galaxies at low z  AGN driven superwinds (AGN)? Rencontres de Moriond

  16. Conclusion • High resolution numerical simulations + simple model  baryon budget history in the hierarchical scenario • Cosmic rates implies: • t* ≈ 1-5 Gyr close to Kennicutt 1998 consumption time scale: <gas /SFR>=2Gyr • w≈1-3 close to efficiency inferred from Martin 99 outflows • Model overestimates Ω*(z=3). Solutions? IMF? • Individual average SFR seems to imply: • Our standard parameters for galaxies • Superwinds w≈10 in groups. AGN? • Next step: simulations with winds and metals Thank you for your attention and happy skiing! Rencontres de Moriond

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