Diffuse dark and bright objects in the Hubble Deep Field

In the Hubble Deep Field (HDF) we have identified candidate regions where primordial galaxies might be forming. These regions are identified from negative or positive peaks in the difference maps obtained from the HDF maps smoothed over 0." 8 and 4 ". They have apparent V magnitudes typically between 29 and 31 (missing flux below the local average level for the dark objects) and are much fainter than the nearby L-* galaxies. The identified objects are shown to be real in two ways. First, the cross-correlations of these peaks detected in different filters are strong. The bright objects have the cross-correlation lengths of about 0." 3. Second, their autocorrelation functions indicate that these faint diffuse objects are self-clustered. Furthermore, the autocorrelation function for the high-redshift starburst subset of bright objects selected by color, has an amplitude significantly higher than that of the total sample. The subset of objects, dark in the F450W and F606W bandpasses, but bright in F814W, also shows stronger correlation compared to the whole dark sample. This further supports that our samples are indeed physical objects. The amplitude and slope of the angular correlation function of the bright objects indicate that these objects are ancestors of the present nearby bright galaxies. It is shown that the data reduction artifacts cannot be responsible for our sample. We have inspected individual bright objects and noted that they have several tiny spots embedded in extended backgrounds. Their radial light distributions are diverse and quite different from those of nearby bright galaxies. They are likely to be the primordial galaxies at high redshifts in the process of active star formation and merging. The dark objects in general appear smooth. Our subset of the dark objects is thought to be the "intergalactic dark clouds" blocking the background far-UV light (at the rest frame) at high redshifts instead of empty spaces between the first galaxies at the edge of the universe of galaxies.