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Tuesday, 18 October 2011, 14:00 in P8445B
Dr. Yin-Zhe Ma (UBC)
Cosmology on large and small cosmic scales
In this talk, I am going to test the concordance cosmology in three different cosmic scales. (1) On the super-horizon scale, Copi et. al. (2009) have been arguing that the lack of large angular correlations of the CMB temperature field provides strong evidence against the standard, statistically isotropic, LCDM cosmology. I am going to argue that the ad-hoc discrepancy is due to the sub-optimal estimator of the low-l multipoles, and a posteriori statistics, which exaggerates the statistical significance. (2) LCDM model also predict the existence of primordial gravitational wave, for which B-mode polarization will be a powerful tool to distinguish different models of the early Universe; (3) On Galactic scales, Watkins et. al. (2008) shows that the very large bulk flow prefers a very large density fluctuation, which seems to contradict to the LCDM model. We provide a physical explanation for this big bulk flow, based on the assumption that CMB frame does not coincide with matter rest frame, resulting in the tilted Universe. We show that the 'tilted Universe' could well explain the bulk flow phenomena and more importantly, the constraints for this tilted Universe can lead to the constraint on the number of e-folds of inflation; (4) In addition, cosmic Mach Number from peculiar velocity catalog may provide a powerful test of the growth of the structure.
Seminars in 2011:
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Modified by Andrei Frolov <frolov@sfu.ca> on 2023-11-01