An Isocurvature Model for Early Galaxy Assembly

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Abstract
The evidence for early assembly of the central parts of the giant galaxies is a challenge for the adiabatic cold dark matter (CDM) model for structure formation; it more readily fits an isocurvature version where homogeneity is broken by CDM that is the remnant of a massive scalar field frozen from quantum fluctuations during inflation. In this picture the primeval CDM mass distribution is proportional to the square of a random Gaussian process, so for a given power spectrum the prominent upward density fluctuations have contrast about three times that of a Gaussian process. This could lead to the assembly of spheroids at redshift z ~ 10 in concentrations outside of which generally smaller fluctuations become the Lyα forest at z ~ 3 and dwarf galaxies at z ~ 1, as the evidence suggests.

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