The power spectrum of dark matter halos in a CDM universe

Abstract

It has been suggested that a COBE‐normalized ‘‘standard’’ cold dark matter (CDM) universe has too much power on small scales compared to the power spectrum of IRAS galaxies. We present the results of an N‐body simulation of such a universe and compare the redshift space P(k) for dark matter halos to that of the IRAS and CfA galaxies. Over the scales that can be investigated in the simulation, P(k) for halos with overdensities δ∼250 is in excellent agreement with P(k) for the IRAS galaxies. P(k) for halos with overdensities δ∼2000 (a more ‘‘biased’’ tracer of the mass than the δ∼250 halos) is in moderately good agreement with P(k) for the CfA galaxies. Assuming one luminous galaxy per dark matter halo, we do not find an excess small‐scale power problem for galaxies in a COBE‐normalized standard CDM universe.