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T. Dolch (JHU), H.C. Ferguson (STScI)
The number densitites of galaxies (galaxies/deg2/magnitude) as a function of magnitude can be an excellent test of evolutionary and large-scale structure models. Measurements of counts across a wide spectral range can help constrain the evolution of dust and star formation, and may even provide constraints on the globally-averaged initial mass function. Comparisons of the integrated light from resolved galaxies to measurements of the diffuse background are also important for understanding galaxy evolution and assessing the importance of low-surface brightness structures to the overall stellar mass density of the universe. Here we compare number counts from recent galaxy surveys, correcting for their differing passbands by adopting first-order changes in the typical galaxy template with respect to magnitude. Surveys used include the Sloan Digital Sky Survey, the Great Observatories Origins Deep Survey, the Hubble Ultra-Deep Field, and a number of other projects. The observed spectral bands range from U-band optical to K-band infrared. With some assumptions about galaxy sizes and surface-brightness profiles, we attempt to account for the light missed in standard photometric estimates, and integrate the resulting corrected counts to estimate the total extra-galactic background due to resolved galaxies.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.