AAS 197, January 2001
Session 65. Galaxy Evolution: High Redshift
Oral, Tuesday, January 9, 2001, 1:30-3:00pm, Pacific One

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[65.01] Morphologies of Distant Galaxies at the Diffraction Limit of the Keck Telescope

T.M. Glassman, J.E. Larkin (UCLA)

Many of the problems of galaxy formation and evolution have remained unanswered because of our inability to observe early galaxies with sufficient angular resolution. Even by modest redshifts (~0.5), ground based telescopes can only marginally resolve galaxies with traditional techniques. Adaptive Optics (AO) systems provide real time compensation of the blurring effects of the Earth's atmosphere and can improve the resolution by more than a factor of ten. The new generation of 8-10 meter ground-based telescopes, when equipped with AO systems, provide close to four times the resolution of the Hubble Space Telescope. The application of AO to extragalactic targets, however, has been very limited due to the need for a relatively bright star to measure the atmospheric distortion.

We report here on a unique program to take advantage of the high density of galaxies on the sky in order to find targets near appropriate guide stars. There are on average 2 galaxies with K<20 mag within 20" of any star. These objects form a statistically unbiased set of galaxies at z~0.4-1 and provide an excellent sample for studying galaxy evolution.

Fourteen galaxies have been imaged with AO in the first year of the program, nine of these in multiple near-infrared bands. The surface brightnesses and scale lengths of these galaxies' disks and bulges have been measured, and these parameters have been compared with values from local surveys to detect galaxy evolution. All the galaxy profiles are smooth and only one secondary knot is detected, indicating a small fraction of strong interactions or merging systems.

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