Peculiar Velocities and Large Scale Flows as Probes of Gravity, ΛCDM and the Growth of Structure over Cosmic Time

Abstract

Peculiar velocities are possibly the most powerful probes of very large-scale mass density fluctuations in the nearby Universe. When coupled with a density field they also can constrain the growth factor of the universe by measuring the proportionality constant between observed velocities and linear theory predicted velocities. In this thesis, I measure a bulk flow of SN within 20,000 km s^1 of 197 +/- 56 km s^1 in direction l = 295 deg +/- 16deg, b = 11deg +/- 14deg , which is consistent with predictions of ΛCDM for large scale mass density fluctuations. Using the IRAS Point Source Catalog Redshift survey (PSCz) galaxy density field and the SNe peculiar velocities I calculated Ω^55_m σ8 to be 0.40 +/- 0.07 which is in excellent agreement with the results of WMAP7: Ω^55_m σ8 = 0.39 +/-0.04. By combining my measured value of with results from other studies, I measure the growth factor γ to be = 0.621 +/- 0.08 which is consistent with Λ CDM's prediction of 0.55. I conclude by exploring some of the systematic errors that could have affected my measurements of β. I find that when β is measured using a reconstruction method the result can be underestimated by between 7 and 15 %.