Are Hubble Deep Field Galaxy Counts Whole Numbers?
  We compute the two-point angular correlation function and number-magnitude relation of Hubble Deep Field sources in order to assess their nature. We find that the correlation peaks between 0.25 arcsec and 0.4 arcsec with amplitude of 2 or greater, and much more for the smallest objects. This angular scale corresponds to physical scales of order 1 kpc for redshifts z > 1. The correlation must therefore derive from objects with subgalaxian separations. At faint magnitudes, the counts satisfy the relation Number prop. to 1/flux, expected for images which are subdivisions of larger ones. A conservative conjecture may explain these results. Since high redshift space (z > 0.5) dominates the volume of the sample, observational redshift effects are important. The K-correction and surface brightness dimming of diffuse sources enhances the prominence of compact, unresolved, UV-bright objects, such as star-forming regions within normal gas-rich galaxies. If such regions appear as individual sources, they could explain the subgalaxian correlation. 
Wesley N. Colley, James E. Rhoads, Jeremiah P. Ostriker (Princeton   University Department of Astrophysical Sciences) and Da...