Candidate Primeval Galaxies in the Hubble Deep Field

TL;DR

This paper identifies candidate high-redshift galaxies in the Hubble Deep Field using the Ly-break technique, revealing their properties and suggesting they are merging systems in early galaxy formation stages.

Contribution

The study presents the first candidate high-redshift galaxies selected via Ly-break in the Hubble Deep Field, providing insights into early galaxy formation processes.

Findings

8 candidate galaxies identified at 2.6 < z < 3.9

Objects are brighter than L* but smaller than nearby galaxies

All candidates show disturbed morphologies indicative of merging

Abstract

We present the results of colour-selection of candidate high redshift (2.6 $<$ z $<$ 3.9) galaxies within the Hubble Deep Field based on the Ly-break at 912\AA . We find 8 such objects in the region, giving a comoving number density comparable to that of nearby bright galaxies (for a flat q$_0$=0.5, H$_0$=100 kms$^{-1}$Mpc$^{-1}$ universe). We provide basic data on the properties of these objects, and show that despite their absolute magnitude being significantly brighter than L$^*$ (typically M$_B$ = -22), they are generally smaller than nearby galaxies. Furthermore, visual inspection of their images shows that they are all highly disturbed systems, with multiple nuclei, tails and plumes, suggesting that they are undergoing merging processes similar to most nearby starburst galaxies. Theoretical models suggest that galaxies form by accumulation of numerous subcomponents, and we suggest that we are seeing this process underway in these objects. It is thus possible that the epoch of galaxy formation might have been discovered.