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Tuesday, 8 October 2013, 14:00 in P8445B
Dr. Yin-Zhe Ma (UBC)
Cosmic peculiar velocity field
The peculiar velocity field is one of the important probe of large scale structure. Its prediction from linear perturbation theory of $\Lambda$CDM should be rigorous tested against observational data. In this talk, I will describe several statistical modeling that can utilize peculiar velocity field data to constrain cosmology. The first method is the cosmic Mach number, which quantify the ratio between bulk flow velocity and velocity dispersion which can be used as a sensitive test of growth of structure. We then constructed a hyper-parameter statistical method, to quantify the difference between the predicted velocity field from the density field probed by IRAS survey, and the direct measurement of galaxy velocities. We show that the hyper-parameter combination of ENEAR, Type-Ia supernovae and SFI++ catalogues can give a constraint on the amplitude of perturbation fσ8 = 0.38 ± 0.05, which is consistent with all other different measurements. If primordial non-Gaussianity exists on large scales, the difference between peculiar velocity field and linear-reconstructed density field will be differerent by a scale-dependent bias factor. We apply the state-of-art observational data and set up a constraint on fNL which is close to other large scale structure constraints. In addition, we provide an explanation of previously found large amplitude of bulk flow. We find that the bulk flow on 50 Mpc/h scales cannot provide strong evidence against LCDM model.
Seminars in 2013:
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Modified by Andrei Frolov <frolov@sfu.ca> on 2023-11-01