2007/03/30 by C. L. Carilli, Ran Wang, M. B. van Hoven +7 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Galaxy #Giant Metrewave Radio Telescope #Intergalactic medium #Lyman limit #Physics #Quasar #Radio galaxy #Redshift #Reionization #astro-ph
paper · pdf · doi:10.1086/518436
published as Astron.J.133:2841-2845,2007 · accepted to the Astronomical Journal; 7 figures; 9 pages aastex format
arxiv created 2007/03/30 · openalex publication_date 2007/05/02 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We have searched for H I 21 cm absorption toward the two brightest radio AGNs at high redshift, J0924-2201 at z = 5.20 and J0913+5919 at z = 5.11, using the Giant Metrewave Radio Telescope. These data set a 3 σ upper limit to absorption of <30% at 40 km s -1 resolution for the 30 mJy source J0913+5919, and <3% for the 0.55 Jy source J0924-2201 at 20 km s -1 resolution. For J0924-2201, limits to broader lines at the few percent level are set by residual spectral baseline structure. For J0924-2201 the column density limit per 20 km s -1 channel is N (H ) < 2.2 × 10 18 T s cm -2 over a velocity range of -700 to +1180 km s -1 centered on the galaxy redshift determined through CO emission, assuming a covering factor of 1. For J0913+5919 the column density limit per 40 km s -1 channel is N (H ) < 2.2 × 10 19 T s cm -2 within ±2400 km s -1 of the optical redshift. These data rule out any cool, high column density H I clouds within roughly ±1000 km s -1 of the galaxies, as are often seen in compact steep-spectrum radio AGNs, or clouds that might correspond to residual gas left over from cosmic reionization.