The DWT Power Spectrum of the two-degree Field Galaxy Redshift Survey.

The power spectrum of the two-degree Field Galaxy Redshift Survey (2dFGRS) sample is estimated with the discrete wavelet transform (DWT) method. The DWT power spectra within 0.035<k<2.2hMpc-1 are measured for three volume-limited samples defined in connective absolute magnitude bins -19∼-18, -20∼-19 and -21∼-20. We show that the DWT power spectrum can effectively distinguish ΛCDM models of σ8 = 0.84 and σ8 = 0.74. We adopt maximum likelihood method to perform three-parameter fitting with bias parameter b, pairwise velocity dispersion σpv and redshift distortion parameter β = Ωm0.6/b to the measured DWT power spectrum. Fitting results denotes that in a σ8 = 0.84 universe the best fitted Ωm given by the three samples are consistent in the range 0.28∼0.36, and the best fitted σpv are 398-27+35, 475-29+37 and 550±20 km/s for the three samples, respectively. However in the model of σ8 = 0.74, our three samples give very different values of Ωm. We repeat the fitting by using empirical formula of redshift distortion. The result of the model of low σ8 is still poor, especially, one of the best value σpv is as large as 103 km/s. We also repeat our fitting by incorporating scale dependence galaxy bias, which gives slightly lower value of Ωm. Differences between models of σ8 = 0.84 and σ8 = 0.74 still exist in the fitting results. The power spectrum of 2dFGRS seems in disfavor of models with low amplitude of density fluctuations if bias parameter is assume to be scale independent. For the fitting value of Ωm to be consistent with that given by WMAP3, strong scale dependence of bias parameters are needed. [ABSTRACT FROM AUTHOR]