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Evolution of the Halo Mass Function

Evolution of the Halo Mass Function. Zarija Luki ć (UIUC) Katrin Heitmann (LANL) Salman Habib (LANL) Sergei Bashinsky (LANL) Paul Ricker (UIUC). astro-ph/0702360. Mass function. Distribution of masses in the Universe: bin all objects (halos) in mass bins – dn/dM

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Evolution of the Halo Mass Function

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  1. Evolution of the Halo Mass Function Zarija Lukić (UIUC) Katrin Heitmann (LANL) Salman Habib (LANL) Sergei Bashinsky (LANL) Paul Ricker (UIUC) astro-ph/0702360

  2. Mass function • Distribution of masses in the Universe: bin all objects (halos) in mass bins – dn/dM • Or, presenting it in a redshift (+cosmology) independent way : where σ is the mass variance: ∞ ∫ σ2(M) = P(k) W2(k;M) k2 dk 0

  3. Why Bothering? • At low redshifts (z ≤ 2) is used for constraining the dark energy properties (Ωλ,w) • - At high redshift is used for quasar abundances & formation sites, reionization history and first stars studies • At high redshift (2006) data from different groups differ by a factor of few!

  4. Simulations • MC2: Particle-Mesh code, tested against other well known cosmo codes (Heitmann et al. 2005, 2007) • 2563 DM particles on 10243 grid • Large set of simulations (60) : 1) Different box sizes (4 – 256 Mpc/h) 2) Many realizations of the same box size • That enables us to : 1) Obtain excellent statistics 2) Probe large range of masses (107 – 1014 h-1 M☼) and redshifts (0 – 20).

  5. Visualization – 90 Mpchttp://tsoodzil.astro.uiuc/~zlukic/mc2_z=0.mov

  6. FOF mass correction Ncorr = N (1-N-0.6) (Warren et al.2006) - Very important for interpreting data!

  7. Results

  8. Universality?

  9. Extended Press-Schechter ∞ ∞ fbias-ps= fps(δc-δ(R), σ2-σ2(R)) -- Bond et al. 1991

  10. EPS correction

  11. Box-corrected MF

  12. Corollary • Need FOF number of particles correction, and to account for finite box correction, especially for high z • - Warren et al. fit gives prediction with 10% accuracy for a wide range of masses and redshifts (ST very good as well) • Good evidence for the universality in CDM phase • (z ≥ 5) • Possible breaking of universality with entrance of dark energy? • - For more check: astro-ph/0702360

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