Cosmological constraint from the 2dF QSO spatial power spectrum

We obtain constraints on the cosmological density parameters, Ω_m and Ω_b, by comparing the preliminary measurement of the quasi-stellar object (QSO) power spectrum from the Two-Degree Field (2dF) QSO Redshift (2QZ) survey with results from an analytic technique of power spectrum estimation, described herein. We demonstrate the validity of the analytic approach by comparing the results with the power spectrum of an N-body simulation. We find a better fit to the shape of the QSO power spectrum for low-density models with Ω_m = 0.1-0.4. We show that a finite baryon fraction Ω_b/Ω_m = 0.2, consistent with observations of the cosmic microwave background anisotropies and nucleosynthesis, fits the observational result of the 2QZ survey better, though the constraint is not very tight. By using the Fisher matrix technique, we investigate just how large a survey would be required before a significant constraint on the density parameters could be obtained. We demonstrate that the constraint could be significantly improved if the survey was four times larger.