STUDIESof the formation and early history of galaxies have been hampered by the difficulties inherent in detecting faint galaxy populations at high redshift. As a consequence, observations at the highest redshifts (z = 3.5-5) have been restricted to objects that are intrinsically bright. These include quasars, radio galaxies, and some Lyman-α-emitting objects1-3 that are very close to (within ~10kpc)-and appear to be physically associated with-quasars. But the extremely energetic processes which make these objects easy to detect also make them unrepresentative of normal (field) galaxies. Here we report the discovery of two Lyman-α-emitting galaxies at redshift z = 4.55, which are sufficiently far from the nearest quasar (~700kpc) that radiation from the quasar is unlikely to provide the excitation source of the Lyman-α emission. Instead, these galaxies appear to be undergoing their first burst of star formation, at a time when the Universe was less than one billion years old.
- Pub Date:
- July 1996
- 8 pages, 1 landscape table, and 3 PostScript figures. Uses aaspp4.sty, flushrt.sty, aj_pt4.sty, overcite.sty (style macros available from xxx.lanl.gov) Figure 1 is bitmapped to 100 dpi. The original PostScript version of Fig. 1 is available via anonymous ftp to ftp://hubble.ifa.hawaii.edu/pub/preprints To appear in Nature