Normalization of the Matter Power Spectrum via the Ellipticity Function of Giant Galaxy Voids from Sdss Dr5

The ellipticity function of cosmic voids exhibits strong dependence on the amplitude of the linear matter power spectrum. Analyzing the most recent void catalogs constructed by Foster and Nelson from the fifth data release of the Sloan Digital Sky Survey, we measure observationally the ellipticity function of giant galaxy voids. Then, we incorporate the redshift distortion and galaxy bias effect into the analytic model of the void ellipticity function and fit it to the observational result by adjusting the value of the power-spectrum normalization with the help of the generalized χ-minimization method. The best-fit normalization of the linear power spectrum is found to be σ8 = 0.90 ± 0.04. Our result is higher than the WMAP σ8-value but consistent with that from the recent work of Liu and Li who have constructed a new improved CMB map independently. Subject headings: cosmology:theory — large-scale structure of universe