Large-Scale Clustering of Sloan Digital Sky Survey Quasars: Impact of the Baryon Density and the Cosmological Constant

We report the first result of the clustering analysis of Sloan Digital SkySurvey (SDSS) quasars. We compute the two-point correlation function (2PCF) ofSDSS quasars in redshift space at $8h^{-1}{\rm Mpc} < s < 500h^{-1}{\rm Mpc}$,with particular attention to its baryonic signature. Our sample consists of19986 quasars extracted from the SDSS Data Release 4 (DR4). The redshift rangeof the sample is $0.72 \le z \le 2.24$ (the mean redshift is $\bar z = 1.46$)and the reddening-corrected $i$-band apparent magnitude range is $15.0 \lem_{i,{\rm rc}} \le 19.1$. Due to the relatively low number density of thequasar sample, the bump in the power spectrum due to the baryon density,$\Omega_{\rm b}$, is not clearly visible. The effect of the baryon density is,however, to distort the overall shape of the 2PCF.The degree of distortionmakes it an interesting alternate measure of the baryonic signature. Assuming ascale-independent linear bias and the spatially flat universe, i.e.,$\Omega_{\rm b} + \Omega_{\rm d} + \Omega_\Lambda =1$, where $\Omega_{\rm d}$and $\Omega_\Lambda$ denote the density parameters of dark matter and thecosmological constant, we combine the observed quasar 2PCF and the predictedmatter 2PCF to put constraints on $\Omega_{\rm b}$ and $\Omega_\Lambda$. Ourresult is fitted as $0.80- 2.8\Omega_{\rm b} < \Omega_\Lambda < 0.90 -1.4\Omega_{\rm b}$ at the 2$\sigma$ confidence level, which is consistent withresults from other cosmological observations such as WMAP. (abridged)Comment: 26 pages, 12 figures, Accepted for publication in the PAS