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The WHIM In Leiden

The WHIM In Leiden. Joop Schaye. Can we find the missing baryons?. Most of the WHIM (10^5-10^7 K) is only moderately overdense Most of the WHIM is metal-poor Metallicity is highly stochastic. Studies using metal emission and (less so) absorption will give a highly biased view.

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The WHIM In Leiden

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  1. The WHIM In Leiden Joop Schaye

  2. Can we find the missing baryons? • Most of the WHIM (10^5-10^7 K) is only moderately overdense • Most of the WHIM is metal-poor • Metallicity is highly stochastic Studies using metal emission and (less so) absorption will give a highly biased view.

  3. Can we find the missing baryons? • Using metal lines, it is impossible to measure Ω(WHIM) more precisely than the metal distribution • Measurements of Ω(WHIM) are only interesting if the errors are smaller than a factor 2 • Simulations can predict Ω(WHIM) to within a factor 2, but not the metal distribution • Turn the problem around! • Analogy: Ω(baryon) at z=3 from the Lyα-forest

  4. What can we learn from the WHIM? • Astrophysics rather than cosmology: • Metal distribution • Cooling in clusters and around galaxies • Feedback from galaxies • Strategies: • Look around galaxies (stack!) rather than blank fields • Need decent angular resolution

  5. But can we really predict Ω(WHIM) ? • Heating and cooling depend on simulation dynamic range • Cooling depends on metallicity • Cooling depends on relatitve abundances • Cooling depends on UV radiation

  6. Collisional Ionization Equilibrium

  7. Photoionization Equilibrium

  8. But can we really predict Ω(WHIM) ? • Have a very large dynamic range • Include chemodynamics • Compute cooling element-by-element • Include photo-ionization of all elements We need cosmological hydro simulations that:

  9. OWLS:OverWhelmingly Large Simulations 10 M CPU hours awarded

  10. The software: Gadget II (SPH) + Chemodynamics (AGB, SNe Ia and II, 11 elements) + Cooling by element and incl. photoionization + New subgrid SF + New wind model + Quasar feedback

  11. The simulations • Cosmological, Hydro (radiative transfer under development) • 2xN3, N up to ~1000, most ~500 • Many runs with varying physics • Aim to “resolve” all galaxies that cool via atoms • Aim to resolve Jeans scale at SF threshold

  12. The science • Nearly everything (on scales 1 kpc < L < 100 Mpc) Strengths: Hydro, abundances, cooling • Examples: • Feedback processes and galaxy formation • WHIM • Clusters

  13. The OWLS people • Leiden: Schaye (PI), Dalla Vecchia, Haas, Wiersma • MPA: Springel • Durham: Theuns • SISSA: Tornatore And: The VIRGO collaboration for zoomed simulations

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