We present a power spectrum analysis of the final 2dF Quasi-Stellar Object (QSO) Redshift Survey catalogue containing 22 652 QSOs. Utilizing the huge volume probed by the QSOs, we can accurately measure power out to scales of ~500 h-1 Mpc and derive new constraints, at z~ 1.4, on the matter and baryonic contents of the Universe. Importantly, these new cosmological constraints are derived at an intermediate epoch between the cosmic microwave background observations at z~ 1000, and local (z~ 0) studies of large-scale structure; the average QSO redshift corresponds to a look-back time of approximately two-thirds of the age of the Universe. We find that the amplitude of clustering of the QSOs at z~ 1.4 is similar to that of present-day galaxies. The power spectra of the QSOs at high and low redshift are compared and we find little evidence for any evolution in the amplitude. Assuming a Λ cosmology to derive the comoving distances, r(z), to the QSOs, the power spectrum derived can be well described by a model with shape parameter Γ= 0.13 +/- 0.02. If an Einstein-de Sitter model r(z) is instead assumed, a slightly higher value of Γ= 0.16 +/- 0.03 is obtained. A comparison with the Hubble Volume Λ cold dark matter (CDM) simulation shows very good agreement over the whole range of scales considered. A standard (Ωm= 1) CDM model, however, predicts a much higher value of Γ than is observed, and it is difficult to reconcile such a model with these data. We fit CDM model power spectra (assuming scale-invariant initial fluctuations), convolved with the survey window function, and corrected for redshift space distortions, and we find that models with baryon oscillations are slightly preferred, with the baryon fraction Ωb/Ωm= 0.18 +/- 0.10. The overall shape of the power spectrum provides a strong constraint on Ωmh (where h is the Hubble parameter), with Ωmh= 0.19 +/- 0.05.
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2003
- quasars: general;
- cosmology: observations;
- large-scale structure of Universe;
- 14 pages, 13 figures. Accepted for publication in MNRAS