The I-band Tully-Fisher relation and large-scale motions in the universe

Author: Han, Mingsheng

Year: 1991

Degree: Dissertation (Ph.D.)

Advisor: Mould, Jeremy R.

Committee Members: Mould, Jeremy R.; Goldreich, Peter Martin; Blandford, Roger D.; Phinney, E. Sterl

Option: Astronomy

DOI: 10.7907/85nr-2g69

Abstract

The ultimate goal of this thesis is to better understand the large-scale motions in the universe on scales beyond the Local-Supercluster, and also to better understand the Tully-Fisher relation as a distance indicator. Sixteen clusters of galaxies in redshifts range from 3000-10000 kms(-1) are studied as test points of the large-scale velocity field, using the I-band Tully-Fisher relation as distance indicator. A complete observational procedure and techniques of measuring cluster distance using the Tully-Fisher relation is investigated in detail, which involves many general topics in the photometric studies of galaxies. Major discussions and results in the thesis are summarized as:

  1. CCD surface photometry is described in detail. Errors and various effects (extinction, cosmological and seeing) on surface photometry are discussed. I-band surface photometry is carried out for some 280 galaxies in the thesis sample.

  2. The problem of internal absorption in spiral galaxies is investigated; new magnitude and isophotal-diameter corrections for internal absorption are derived.

  3. Different techniques for deriving cluster distances using Tully-Fisher relation are compared; distance bias due to sample selection effects is discussed at length; a Maximum-Likelihood method is given which is able to handle the sample selection effects.

  4. Global photometric properties of the cluster galaxies are examined; the problem of second parameter in the TF relation is investigated; a physical explanation for the TF relation and its dispersion is proposed.

  5. The peculiar velocity field as traced by the sample clusters is found to be highly non-random, and appears to be a coherent flow towards the general direction of the Great Attractor, with a flow amplitude of some 400~600 kms(-1) at the position of the Local Group.

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