by
Luc Simard
B.Sc. Queen's 1990
A Thesis Submitted in Partial Fulfillment of the
Requirements for the Degree of
DOCTOR OF PHILOSOPHY
in the Department of Physics and Astronomy
We accept this thesis as conforming
to the required standard.
Dr. C. J. Pritchet, Supervisor (Department of Physics
& Astronomy)
Dr. F. D. A. Hartwick, Departmental Member (Department of Physics
& Astronomy)
Dr. D. A. Vandenberg, Departmental Member (Department of Physics
& Astronomy)
Dr. P. Driessen, Outside Member (Department of Electrical Engineering)
Dr. D. Crampton, External Examiner (Dominion Astrophysical Observatory)
© Luc Simard, 1996,
University of Victoria.
All rights reserved. Thesis may not be reproduced in whole or in part,
by mimeograph or other means, without the permission of the author.
A dilemma is posed by studies of galaxy evolution at intermediate
redshifts. If evolutionary effects are neglected, simple models predict
number densities of faint galaxies which are 2
5
lower than
observed at z 
0.4. Yet the faint galaxy redshift distribution
appears to be well modelled by the same noevolution models.
If low-mass starbursting galaxies are responsible for the excess, then the
excess faint galaxy population should have rotation velocities lower
than those of quiescent galaxies with the same luminosity.
This thesis describes the results of a limited survey of the
internal kinematics of intermediate
redshift (z = 0.250.45) field galaxies. The goal of this survey was to find the
unmistakable kinematical signature of low-mass starbursting galaxies.
Using the Canada-France-Hawaii Telescope,
spatially-resolved spectra of the [O II] 
37263729
Ådoublet emission line have been obtained for 22 galaxies.
Highspatial resolution has made it possible to extract V
sin 
and
[O II] disk scale length from each galaxy spectrum using synthetic galaxy rotation
curve fitting.
It is found that about 25
of the galaxies in the sample have [OII] kinematics unrelated to
rotation. [OII] emission is concentrated in the nucleus in these ``kinematically
anomalous'' galaxies. A Doppler ellipse similar to those found in local dwarf irregular galaxies has been
observed in a z = 0.35 galaxy.
An intermediate redshift Tully-Fisher (TF) relation defined by 12
kinematically normal galaxies shows that these galaxies have a systematically lower rotation velocity (i.e. mass)
for their luminosity than expected from the local TF relation. These
galaxies would have to fade by 
1.52 mag to lie on the local TF relation. This is consistent with
starbursting dwarf galaxy models. Although the sample is small, there is also a hint that massive galaxies do not lie as
far off the local TF relation as low-mass ones. However, as shown using a large sample of local galaxies, the scatter in the local
TF relation is large, especially for late-type galaxies. Selection effects, particularly [OII] emission strength, could be responsible for part of the observed TF shift if different star formation rates are responsible for the local TF scatter. A comparison with other works indicates that the luminosity-dependent luminosity evolution scenario neatly explains all the available internal kinematics and surface brightness data.
Examiners:
Dr. C. J. Pritchet, Supervisor (Department of Physics
& Astronomy)
Dr. F. D. A. Hartwick, Departmental Member (Department of Physics
& Astronomy)
Dr. D. A. Vandenberg, Departmental Member (Department of Physics
& Astronomy)
Dr. P. Driessen, Outside Member (Department of Electrical Engineering)
Dr. D. Crampton, External Examiner (Dominion Astrophysical Observatory)