Correlated Adiabatic and Isocurvature Cosmic Microwave Background Fluctuations in the Wake of the Results from the Wilkinson Microwave Anisotropy Probe
Abstract
In general correlated models, in addition to the usual adiabatic component with a spectral index n_{ad1} there is another adiabatic component with a spectral index n_{ad2} generated by entropy perturbation during inflation. We extend the analysis of a correlated mixture of adiabatic and isocurvature cosmic microwave background fluctuations of the Wilkinson Microwave Anisotropy Probe (WMAP) group, who set the two adiabatic spectral indices equal. Allowing n_{ad1} and n_{ad2} to vary independently we find that the WMAP data favor models where the two adiabatic components have opposite spectral tilts. Using the WMAP data only, the 2σ upper bound for the isocurvature fraction f_{iso} of the initial power spectrum at k_{0}=0.05 Mpc^{1} increases somewhat, e.g., from 0.76 of n_{ad2}=n_{ad1} models to 0.84 with a prior n_{iso}<1.84 for the isocurvature spectral index.
 Publication:

Physical Review Letters
 Pub Date:
 September 2003
 DOI:
 10.1103/PhysRevLett.91.131302
 arXiv:
 arXiv:astroph/0304175
 Bibcode:
 2003PhRvL..91m1302V
 Keywords:

 98.70.Vc;
 98.80.Cq;
 Background radiations;
 Particletheory and fieldtheory models of the early Universe;
 Astrophysics;
 High Energy Physics  Phenomenology
 EPrint:
 5 pages, 7 figures. V2: Added 2 figures and revised a bit the results section. This is a slightly longer version than the published one in PRL