The epoch of structure formation in blue mixed dark matter models

Abstract

Recent data on the high--redshift abundance of damped Ly$\alpha$ systems are compared with theoretical predictions for `blue' (i.e. $n>1$) Mixed Dark Matter models. The results show that decreasing the hot component fraction ${\Omega }_{\nu }$ and/or increasing the primordial spectral index $n$ implies an earlier epoch of cosmic structure formation. However, we also show that varying ${\Omega }_{\nu }$ and $n$ in these directions makes the models barely consistent with the observed abundance of galaxy clusters. Therefore, requiring at the same time observational constraints on damped Ly$\alpha$ systems and cluster abundance to be satisfied represents a challenge for the Mixed Dark Matter class of models.

Uuencoded compressed tar file containing 6 page TeX file and 4 postscript figures. Uses mn.sty and psfig.sty. To appear in MNRAS. Main change: inclusion of a discussion of the constraints coming from the cluster abundances

Cited by in corpus (7)

• Light Gravitinos as Mixed Dark Matter
• The Formation of Cosmic Structures in a Light Gravitino Dominated Universe
• Constraining the Power Spectrum using Clusters
• The Gravitational-Wave contribution to the CMB anisotropies
• Cosmology Using Cluster Internal Velocity Dispersions
• Mixed Models with n>1 and Large Scale Structure constraints
• Searching for blue in the dark