1999/04/21 by Wil van Breugel, Carlos De Breuck, C. De Breuck +7 · 10 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/312080
11 Pages, including 3 PostScript figures. Accepted for publication in the Astrophysical Journal Letters
arxiv created 1999/04/21 · openalex publication_date 1999/06/20 · arxiv updated 2009/12/01 · openalex created_date 2022/10/04 · openalex updated_date 2026/08/01
We report the discovery of the most distant known active galactic nucleus, the radio galaxy TN J0924-2201 at z =5.19. The radio source was selected from a new sample of ultrasteep spectrum sources, has an extreme radio spectral index α =-1.63, and is identified at near-IR wavelengths with a very faint, K =21.3±0.3 object. Spectroscopic observations show a single emission line at λ~7530 Å, which we identify as Lyα. The K -band image, sampling rest-frame U band, shows a multicomponent, radio-aligned morphology, which is typical of lower-redshift radio galaxies. TN J0924-2201 extends the near-IR Hubble, or K - z , relation for powerful radio galaxies to z >5 and is consistent with models of massive galaxies forming at even higher redshifts.