A RADIO GALAXY AT REDSHIFT-4.41

THE most distant astronomical objects observed are quasars at redshift s of z approximate to 4.9 (ref. 1), corresponding to a time when the U niverse was less than a billion years old. This leaves little time dur ing which the quasars and their host galaxies could form(2). In princi ple, the evolutionary state of the host galaxies can be probed by dete rmining how many stars have formed, but this task is not straightforwa rd because light from the quasar itself overwhelms any accompanying st arlight. High-redshift radio galaxies-the likely progenitors of lumino us elliptical galaxies(3)-provide better targets for such studies, as optical emissions from their active nuclei are observed to be faint. H ere we report the discovery of a radio galaxy (6C0140 + 326) at z = 4. 41 which shows no evidence for either a stellar continuum or an unobsc ured quasar nucleus. We conclude that the galaxy associated with the r adio source is neither fully formed nor obviously in the process of fo rming stars, This implies that at least some giant elliptical galaxies are still immature at z approximate to 4.5, and that if the intense b ursts of star formation thought to produce the bulk of their stellar p opulations occur during the radio-bright phase, these star-forming reg ions are obscured by dust and gas.