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

• Main Author: Turnbull, Stephen
• Language: en
• Published: 2012
• Subjects: Gravity; ΛCDM; Peculiar Velocities; Growth of Structure; Physics
• Online Access: http://hdl.handle.net/10012/7079

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 %.