Large-scale structure formation for power spectra with broken scale invariance

Abstract

We have simulated the formation of large-scale structure arising from COBEnormalized spectra computed by convolving a primordial double-inflation perturbation spectrum with the CDM transfer function. Due to the broken scale invariance ('BSI') characterizing the primordial perturbation spectrum, this model has less small-scale power than the (COBE-normalized) standard CDM model. The particle-mesh code (with 512 3 cells and 256 3 particles) includes a model for thermodynamic evolution of baryons in addition to the usual gravitational dynamics of dark matter. It provides an estimate of the local gas temperature. In particular, our galaxy-finding procedure seeks peaks in the distribution of gas that has cooled. It exploits the fact that "cold" particles trace visible matter better than average and thus provides a natural biasing mechanism. The basic picture of large-scale structure formation in the BSI model is the familiar hierarchical clustering scenario. We obtain particle in cell statistics, the galaxy correlation function, the cluster abundance and the cluster-cluster correlation function and statistics for large and small scale velocity fields. We also report here on a semi-quantitative study of the distribution of gas in different temperature ranges. Based on confrontation with observations and comparison with standard CDM, we conclude that the BSI scenario could represent a promising modification of the CDM picture capable of describing many details of large-scale structure formation.

Constraints on Cosmological Parameters from the Lyα Forest Power Spectrum andCOBEDMR

“…Prominent among these variants are models with a time-varying scalar Ðeld, also known as "" quintessence ÏÏ (e.g., Peebles & Ratra 1988 ;Wang & Steinhardt 1998), models in which the energy of the radiation background has been boosted above its standard value by a decaying particle species (qCDM models ; e.g., Bond & Efstathiou 1991), and models in which inÑation produces a power spectrum with broken scale invariance (e.g., Kates et al 1995). Given the observational evidence for a negative pressure component from Type Ia supernovae (Riess et al 1998 ;, the quintessence family might be especially interesting to explore in future work.…”

Superlarge-scale structure inN-body simulations

“…The BCDM is specified by two parameters, the location of the break at k break −1 =1.5 h −1 Mpc, and the relative power on both sides of the break, Δ=3. These parameters were originally chosen to obtain optimal linear fits to the various large‐scale structure observations (Gottlöber, Mücket & Starobinsky 1994), and later tested against N ‐body simulations (Amendola et al 1995; Kates et al 1995; Ghigna et al 1996; Retzlaff et al 1998). Both TCDM and BCDM models seemed to be promising since they have reduced power at galactic scales with respect to the COBE‐normalized SCDM model.…”

“…For such boxes the formation of the majority of structure elements is described by higher harmonics of the primordial density waves, with l ≥8–10. We use the particle mesh (PM) code, described in more detail in Kates et al (1995) and Retzlaff et al (1998), with N p =300 3 or 256 3 particles in N cell =600 3 or 512 3 grid cells, respectively. These parameters provide a resolution ∼0.9 h −1 Mpc and a mass resolution ∼1–3×10 11 M ⊙ .…”

The Las Campanas Redshift Survey galaxy--galaxy autocorrelation function

“…1, the dashed line denotes the ξgg(s) from the uniformly sampled uLCRS catalogue, and the dotted line denotes the ξgg(s) from the uniformly sampled uLCRS112 catalogue. in 200h −1 Mpc and 150h −1 Mpc boxes for the SCDM/BSI and the ΛCDM simulations, respectively, using a PM code with 128 3 particles in 256 3 grid cells (Kates et al 1995).…”