A radio galaxy at redshift 4.41

The most distant astronomical objects observed are quasars at redshifts of z ≈ 4.9 (ref. 1), corresponding to a time when the Universe was less than a billion years old. This leaves little time during which the quasars and their host galaxies could form2. In principle, the evolutionary state of the host galaxies can be probed by determining how many stars have formed, but this task is not straightforward because light from the quasar itself overwhelms any accompanying starlight. High-redshift radio galaxies—the likely progenitors of luminous elliptical galaxies3—provide better targets for such studies, as optical emissions from their active nuclei are observed to be faint. Here 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 unobscured quasar nucleus. We conclude that the galaxy associated with the radio source is neither fully formed nor obviously in the process of forming stars. This implies that at least some giant elliptical galaxies are still immature at z ≈ 4.5, and that if the intense bursts of star formation thought to produce the bulk of their stellar populations occur during the radio-bright phase, these star-forming regions are obscured by dust and gas