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Title: Determination of the local group gravitational acceleration using all-sky redshift surveys
Author: D'Mellow, Kenton J.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2002
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This thesis aims to give a definitive measure of the velocity on the Local Group from gravitational arguments while attempting to minimise errors in the calculation. Iterative techniques are used to converge on a self consistent solution to the Local Group velocity and surrounding spatial galaxy distribution. To minimise intrinsic survey error, a new dataset - the Behind The Plane (BTP) galaxy redshift survey has been completed and analysed. The BTP is the low-latitude extension to the previously complete Point Source Catalogue redshift (PSCz) survey of galaxies. Near-infrared and radio techniques were used to identify and measure optically obscured galaxies that were excluded from the PSCz, extending overall sky coverage from 84% to 93%. This high degree of sky coverage makes the PSCz + BTP the best available dataset for dynamical studies of the local Universe. The reduction of the gap in sky coverage significantly reduces uncertainty in dynamical predictions, especially as the missing strip behind the Milky Way is known to include the Great Attractor. The major result of this work is the possible discovery of an unexpectedly large mass concentration beyond the Great Attractor, at an approximate distance of cz = 20,000kms-1 in the direct l = 300, b = 0. The misalignment between inferred Local Group velocity vector and the CMB temperature dipole significantly increases, and b parameter estimates yield inconsistency with many other current and reliable estimates in the literature, if this structure is excluded. Upon the inclusion of this concentration, estimates for the Local Group velocity center upon l = 245, b = 30, and yield a value of bIRAS = 0.65. Directional misalignment is consistent to within 2-s, but is robust across significant variation in both the data and calculation method applied.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available