Structure Formation with Generalized Dark Matter
Abstract
The next generation of cosmic microwave background (CMB) experiments, galaxy surveys, and highredshift observations can potentially determine the nature of the dark matter observationally. With this in mind, we introduce a phenomenological model for a generalized dark matter (GDM) component and discuss its effect on largescale structure and CMB anisotropies. Specifying the gravitational influence of the otherwise noninteracting GDM requires not merely a model for its equation of state but one for its full stress tensor. From consideration of symmetries, conservation laws, and gauge invariance, we construct a simple but powerful threecomponent parameterization of these stresses that exposes the new phenomena produced by GDM. Limiting cases include: a particle component (e.g., weakly interacting massive particles, radiation, or massive neutrinos), a cosmological constant, and a scalar field component. Intermediate cases illustrate how the clustering properties of the dark matter can be specified independently of its equation of state. This freedom allows one to alter the amplitude and features in the matterpower spectrum relative to those of the CMB anisotropies while leaving the background cosmology fixed. Conversely, observational constraints on such phenomena can help determine the nature of the dark matter.
 Publication:

The Astrophysical Journal
 Pub Date:
 October 1998
 DOI:
 10.1086/306274
 arXiv:
 arXiv:astroph/9801234
 Bibcode:
 1998ApJ...506..485H
 Keywords:

 COSMOLOGY: COSMIC MICROWAVE BACKGROUND;
 COSMOLOGY: THEORY;
 COSMOLOGY: DARK MATTER;
 LARGESCALE STRUCTURE OF THE UNIVERSE;
 Cosmology: Cosmic Microwave Background;
 Cosmology: Theory;
 Cosmology: Dark Matter;
 largescale structure of the universe;
 Astrophysics
 EPrint:
 13 pages, 10 figures, accepted to ApJ. Typo in eqn (A8) corrected