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G. Mallen-Ornelas (Univ. of Toronto)
The internal kinematics of a galaxy are closely related to its mas, and can provide an insight into the nature of a high-redshift galaxy independent of any changes in appearance that may be caused by bursts of star formation. In particular, kinematic studies can be used to constrain how much luminosity evolution an individual galaxy may have undergone. We have undertaken a survey of the internal kinematics of typical blue L* galaxies at z~0.6. Blue galaxies represent the most strongly evolving population to intermediate redshifts, as seen in the luminosity function from the Canada-France Redshift Survey (CFRS, Lilly et al 1995, ApJ 455, 108). Targets for the present study were selected regardless of size or morphology, and useful kinematic information was obtained for 26 galaxies at 0.1 < z < 0.7, most of them bluer than a local Scd galaxy. Emission lines were used to measure internal velocity dispersion \sigmav, and sizes were measured from HST imaging. We found that galaxies in our sample at z<0.5 have \sigmav, sizes, luminosities, and morphologies similar to those of local galaxies. However, blue galaxies at z>5 have sizes and \sigmav similar to those of local Irregulars --- consistent with their HST morphologies --- but they are generally 1--2 mag brighter than local galaxies of similar size and \sigmav. These results support the idea that the excess of blue L* galaxies at z~0.6 is caused in great part by a population of brightened small late-type galaxies.
The author(s) of this abstract have provided an email address for comments about the abstract: mallen@astro.utoronto.ca