The 2dF QSO Redshift Survey -- XI. The QSO power spectrum

Abstract

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 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 = 0.13 ± 0.02. If an Einstein-de Sitter model r(z) is instead assumed, a slightly higher value of = 0.16 ± 0.03 is obtained. A comparison with the Hubble Volume cold dark matter (CDM) simulation shows very good agreement over the whole range of scales considered. A standard ( m = 1) CDM model, however, predicts a much higher value of 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 b / m = 0.18 ± 0.10. The overall shape of the power spectrum provides a strong constraint on m h (where h is the Hubble parameter), with m h = 0.19 ± 0.05.

Distances of Quasars and Quasar‐like Galaxies: Further Evidence That Quasi‐stellar Objects May Be Ejected from Active Galaxies

“…The space density of detected quasars may still be too low, however, for these plots to show structure; if the 22,600 quasars extend to redshifts near z ¼ 3 and the 205,000 galaxies plotted by Tegmark et al (2004) extend only to z ¼ 0:2, the galaxy/quasar number density ratio per unit volume between these two samples is huge ($8000/1). Although it is true that the QSO power spectrum results of Outram et al (2003) agreed with galaxy results, it is not clear that the discrete features in the redshift distribution that we are discussing here could not have influenced the result. Furthermore, it is difficult to prove that the DIR model would not also give acceptable results since the redshift distribution would be completely new, and only by repeating the analysis using the new distance redshifts of the DIR model could this be determined.…”

“…An analysis of the QSO power spectrum of 22,652 QSOs in the Two-Degree Field (2dF) QSO Redshift Survey catalog has been presented by Outram et al (2003), who found, assuming cosmological redshifts, that the amplitude of clustering of QSOs at a mean redshift of z ¼ 1:4 is similar to that of present-day galaxies. A comparison of the power spectra of QSOs at low and high redshift also showed little evidence for any evolution in the amplitude.…”

A coarse-grained field theory for density fluctuations and correlation functions of galaxies and clusters

“…A real spectrum cannot have an infinitely sharp peak, which should be smoothed by some damping effects. Recent observations have indicated that the measured P(k) has a rather flat peak with large systematic errors on large scales (Outram et al 2003;Padilla & Baugh 2003;Tegmark et al 2004;Maller et al 2005;Percival 2005). …”

Clustering of quasars in SDSS-IV eBOSS: study of potential systematics and bias determination

“…Quasar redshift surveys have often operated in tandem with galaxy surveys, and have highlighted the possibility of using quasars to constrain cosmology at higher redshifts than would be possible for galaxy samples to similar magnitude limits [e.g. [38][39][40].…”