2004/03/23 by Johannes Staguhn, J. G. Staguhn, Eva Schinnerer +3 · 1 citation
Chemistry · Physics and Astronomy · #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Spectroscopy and Laser Applications #astro-ph
paper · pdf · doi:10.1086/421039
published as Astrophys.J. 609 (2004) 85-93 · to be published in ApJ 1 July 2004 issue
arxiv created 2004/03/23 · openalex publication_date 2004/06/21 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We present the first subkiloparsec (~0 7 ≈ 850 pc) resolution 12 CO(1-0) molecular line observations of the interstellar medium (ISM) in the host galaxy of the QSO I Zw 1. The observations were obtained with the BIMA millimeter interferometer in its compact A configuration. The BIMA data are complemented by new observations of the 12 CO(2-1) and 13 CO(1-0) lines with the IRAM Plateau de Bure Interferometer (PdBI) at 0 9 and 2 1 resolution, respectively. These measurements, which are part of a multiwavelength study of the host galaxy of I Zw 1, are aimed at comparing the ISM properties of a QSO host with those of nearby galaxies, as well as to obtain constraints on galaxy formation/evolution models. Our images of the 12 CO(1-0) line emission show a ringlike structure in the circumnuclear molecular gas distribution with an inner radius of about 1.2 kpc. The presence of such a molecular gas ring was predicted from earlier lower angular resolution PdBI 12 CO(1-0) observations. A comparison of the BIMA data with IRAM PdBI 12 CO(2-1) observations shows variations in the excitation conditions of the molecular gas in the innermost 1 5 comprising the nuclear region of I Zw 1. The observed properties of the molecular cloud complexes in the disk of the host galaxy suggest that they may be the sites of massive circumnuclear star formation and show no indications of excitation by the active galactic nucleus (AGN). This all indicates that the molecular gas in a QSO host galaxy has properties similar to the gas observed in nearby low-luminosity AGNs.