260 research outputs found

    Simulation of Cosmic Microwave Background Polarization Fields for AMiBA Experiment

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    We have made a topological study of cosmic microwave background (CMB) polarization maps by simulating the AMiBA experiment results. A Λ\LambdaCDM CMB sky is adopted to make mock interferometric observations designed for the AMiBA experiment. CMB polarization fields are reconstructed from the AMiBA mock visibility data using the maximum entropy method. We have also considered effects of Galactic foregrounds on the CMB polarization fields. The genus statistic is calculated from the simulated QQ and UU polarization maps, where QQ and UU are Stokes parameters. Our study shows that the Galactic foreground emission, even at low Galactic latitude, is expected to have small effects on the CMB polarization field. Increasing survey area and integration time is essential to detect non-Gaussian signals of cosmological origin through genus measurement.Comment: 7 pages, 4 figures, Accepted version for publication in the Journal of the Korean Astronomical Societ

    Cosmic Momentum Field and Mass Fluctuation Power Spectrum

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    We introduce the cosmic momentum field as a new measure of the large-scale peculiar velocity and matter fluctuation fields. The momentum field is defined as the peculiar velocity field traced and weighted by galaxies, and is equal to the velocity field in the linear regime. We show that the radial component of the momentum field can be considered as a scalar field with the power spectrum which is practically 1/3 of that of the total momentum field. We present a formula for the power spectrum directly calculable from the observed radial peculiar velocity data. The momentum power spectrum is measured for the MAT sample in the Mark III catalog of peculiar velocities of galaxies. Using the momentum power spectrum we find the amplitude of the matter power spectrum is 6400^{+2800}_{-1800} and 4500^{+2000}_{-1300} \Omega^{-1.2} (h^{-1} Mpc)^{-3} at the wavenumbers 0.049 and 0.074 h Mpc^{-1}, respectively, where \Omega is the density parameter. The 68% confidence limits include the cosmic variance. The measured momentum and density power spectra together indicate that the parameter \beta_O = \Omega^{0.6}/b_O = 0.51^{+0.13}_{-0.08} or \Omega = 0.33^{+0.15}_{-0.09} b_O^{5/3} where b_O is the bias factor for optical galaxies.Comment: 26 pages, 8 figures, accepted by MNRA
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