2007/02/28 by Michiel Reuland, Wil van Breugel, W. de Vries +17 · 1 citation
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Galaxy #Halo #Interstellar medium #Physics #Radio galaxy #Redshift #Star formation #astro-ph
paper · pdf · doi:10.1086/516571
published as Astron.J.133:2607-2623,2007 · Accepted for publication in AJ (June 2007 issue); 24 pages, 12 figures (reduced in size)
arxiv created 2007/02/28 · openalex publication_date 2007/04/23 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present the results of an optical and near-IR spectroscopic study of giant nebular emission-line halos associated with three z > 3 radio galaxies, 4C 41.17, 4C 60.07, and B2 0902+34. Previous deep narrowband Lyα imaging revealed complex morphologies with sizes up to 100 kpc, possibly connected to outflows and AGN feedback from the central regions. The outer regions of these halos show quiet kinematics with typical velocity dispersions of a few hundred km s -1 and velocity shears that can mostly be interpreted as being due to rotation. The inner regions show shocked cocoons of gas closely associated with the radio lobes. These display disturbed kinematics and have expansion velocities and/or velocity dispersions >1000 km s -1 . The core region is chemically evolved, and we also find spectroscopic evidence for the ejection of enriched material in 4C 41.17 up to a distance of ≈60 kpc along the radio axis. The dynamical structures traced in the Lyα line are, in most cases, closely echoed in the carbon and oxygen lines. This shows that the Lyα line is produced in a highly clumped medium of small filling factor and can therefore be used as a tracer of the dynamics of high-redshift radio galaxies (HzRGs). We conclude that these HzRGs are undergoing a final jet-induced phase of star formation with ejection of most of their interstellar medium before becoming "red and dead" elliptical galaxies.