The Contribution of Normal, Dim, and Dwarf Galaxies to the Local Luminosity Density

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Abstract
From the Hubble Deep Field catalog recently presented by Driver et al., we derive the local (0.3 < z < 0.5) bivariate brightness distribution of field galaxies within a 326 Mpc3 volume-limited sample. The sample contains 47 galaxies which uniformly sample the underlying galaxy population within the specified redshift, magnitude, and surface brightness limits (0.3 < z < 0.5, -21.3 < MB < -13.7 mag, 18.0 < μB < 24.55 mag arcsec-2). We conclude that (1) a luminosity-surface brightness relation exists for both the field and cluster galaxy populations, MB ≈ [(1.5 ± 0.2)μe - (50 ± 2)], (2) luminous low surface brightness galaxies account for less than 10% of the L* population, and (3) low-luminosity low surface brightness galaxies outnumber Hubble types by a factor of ~1.4; however, their space density is not sufficient to explain the faint blue excess either by themselves or as faded remnants. In terms of the local luminosity density and galaxy dynamical mass budget, normal galaxies (i.e., the Hubble tuning fork) contribute 88% and 72%, respectively. This compares to 7% and 12% for dim galaxies and 5% and 16% for dwarf galaxies (within the above specified limits).
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