The Interstellar Medium of IRAS 08572 + 3915 NW : H + 3 and Warm High Velocity CO

We confirm the first detection of the molecular ion H+3 in an extragalactic object, the highly obscured ultraluminous galaxy IRAS 08572+3915 NW. We also have detected absorption lines of the fundamental band of CO in this galaxy. The CO absorption consists of a cold component close to the systemic velocity and warm, highly blueshifted and redshifted components. The warm blueshifted component is remarkably strong and broad and extends at least to -350 km s. Some analogies can be drawn between the H+3 and cold CO in IRAS 08572+3915 NW and the same species seen toward the Galactic center. The profiles of the warm CO components are not those expected from a dusty torus of the type thought to obscure active galactic nuclei. They are probably formed close to the dust continuum surface near the buried and active nucleus and are probably associated with an unusual and energetic event there. Subject headings: galaxies: active — galaxies: individual (IRAS 08572+3915) — galaxies: ISM — infrared: galaxies — line: profiles — molecular processes Based on data obtained at the United Kingdom Infrared Telescope, which is operated by the Joint Astronomy Center on behalf of the U. K. Particle Physics and Astronomy Research Council Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan Gemini Observatory, 670 N. A’ohoku Place, Hilo, HI 96720; [email protected] Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg, Germany Subaru Telescope, Astronomical National Observatory of Japan, 650 N. A’ohoku Place, Hilo, HI 96720 Department of Astronomy and Astrophysics, Department of Chemistry, 5735 S. Ellis Avenue; and Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 Department of Chemistry and Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana IL 61801