Cosmological effects of coupled dark matter
Abstract
Many models have been studied that contain more than one species of dark matter and some of these couple the cold dark matter (CDM) to a light scalar field. In doing this we introduce additional long range forces, which in turn can significantly affect our estimates of cosmological parameters if not properly accounted for. It is, therefore, important to study these models and their resulting cosmological implications. We present a model in which a fraction of the total cold dark matter density is coupled to a scalar field. We study the background and perturbation evolution and calculate the resulting cosmic microwave background anisotropy spectra. The greater the fraction of dark matter coupled to the scalar field and the stronger the coupling strength, the greater the deviation of the background evolution from ΛCDM. Previous work, with a single coupled dark matter species, has found an upper limit on the coupling strength of order O(0.1). We find that with a coupling of this magnitude more than half the dark matter can be coupled to a scalar field without producing any significant deviations from ΛCDM.
 Publication:

Physical Review D
 Pub Date:
 October 2013
 DOI:
 10.1103/PhysRevD.88.083522
 arXiv:
 arXiv:1304.2196
 Bibcode:
 2013PhRvD..88h3522M
 Keywords:

 98.80.k;
 95.35.+d;
 98.80.Cq;
 Cosmology;
 Dark matter;
 Particletheory and fieldtheory models of the early Universe;
 Astrophysics  Cosmology and Extragalactic Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Theory
 EPrint:
 10 pages, 4 figures, minor changes