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

We report on the first result from the clustering analysisof SDSS quasars. We computed the two-point correlation function (2PCF) of SDSS quasarsin redshift space at 8 h −1 Mpc baryonicsignature. Our sample consisted of 19986quasarsextracted from the SDSS Data Release 4. The redshift range of the sample is 0.72 ≤ z ≤ 2.24 (the mean redshift is z =1 .46) and the reddening-correctedi-bandapparent magnituderange is 15.0 ≤ mi,rc ≤ 19.1. Due to the relatively low number density of thequasarsample, the bump in the power spectrum due to thebaryondensity, Ωb, is not clearly visible. The effect of thebaryondensity is, however, to distort the overall shape of the 2PCF. The degree of distortion makes it an interesting alternate measure of thebaryonicsignature. Assuming a scale-independent linear bias and a spatially flat universe, we combined the observedquasar2PCF and the predicted matter 2PCF to put constraints on Ωb and ΩΛ (the cosmological constant). Our result was fitted as 0.80 −2.8Ωb < ΩΛ < 0.90 −1.4Ωb at the 2 σ confidence level. The “mean” bias parameter of ourquasarsample is 1.59 σ8 −1 (for Ωb =0 .04 and ΩΛ =0 .7), where σ8 is the top-hat mass fluctuation amplitude at 8 h −1 Mpc. We also estimated the corresponding bias parameter ofquasarsat z =0 ,bQSO,Fry(0), assuming Fry’s bias evolution model. For Ωb =0 .04, ΩΛ =0 .73, and Ωd =0 .23, we found bQSO,Fry(0) = 0.54 + 0.83 σ8 −1 which is valid for 0.6 <σ 8 < 1.0.< div>

Keywords:

• Astrophysics
• Astronomy
• Dark matter
• Confidence interval
• Cosmological constant
• Physics
• Baryon
• Quasar
• Number density
• Apparent magnitude
• Redshift
• Shape of the universe
• Galaxy
• Cosmology

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