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Sune Toft (Yale)
The high density of galaxies in clusters makes them excellent laboratories for studying galaxy evolution. Clusters in the local Universe are dominated by old massive elliptical galaxies. By studying clusters over a range of redshifts one can trace the evolutionary history of these galaxies, and strongly constrain models of structure formation and evolution. High redshift clusters provide the strongest constraints. This thesis is a detailed observational study of two of the most distant clusters known (at redshifts z=1.00 and z=1.24). Taking advantage of extremely deep near infrared and optical observations obtained with the VLT, I develop a novel method for deriving the K-band luminosity function of the cluster galaxies (which is sensitive to their stellar mass function). The shape of the derived luminosity function is remarkably similar to that derived at similar restframe wavelengths in local clusters, only shifted to brighter magnitudes. This suggests that the massive elliptical galaxies that dominate the bright end of the K-band LF were largely in place at z~1. This is a challenge for current hierarchical models of galaxy formation which predict most of the massive elliptical galaxies to assemble at lower redshifts, but is well described by passive evolution models of galaxies assembled at high redshift (z>2).
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The author(s) of this abstract have provided an email address for comments about the abstract: toft@astro.yale.edu
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.