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Detecting Low-Order CO Emission from z ≳ 4 Quasar Host Galaxies

Published online by Cambridge University Press:  01 August 2006

D. A. Riechers ,
F. Walter ,
C. L. Carilli ,
K. K. Knudsen ,
K.Y. Lo ,
D. J. Benford ,
J. G. Staguhn ,
T. R. Hunter ,
F. Bertoldi  and
C. Henkel
...Show all authors
D. A. Riechers
Affiliation:
Max-Planck-Institut für Astronomie, Heidelberg, Germany
F. Walter
Affiliation:
Max-Planck-Institut für Astronomie, Heidelberg, Germany
C. L. Carilli
Affiliation:
National Radio Astronomy Observatory, Socorro, NM, USA
K. K. Knudsen
Affiliation:
Max-Planck-Institut für Astronomie, Heidelberg, Germany
K.Y. Lo
Affiliation:
National Radio Astronomy Observatory, Charlottesville, VA, USA
D. J. Benford
Affiliation:
Lab. for Observational Cosmology, NASA Goddard Space Flight Center, Greenbelt, MD, USA
J. G. Staguhn
Affiliation:
Lab. for Observational Cosmology, NASA Goddard Space Flight Center, Greenbelt, MD, USA
T. R. Hunter
Affiliation:
Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA
F. Bertoldi
Affiliation:
Argelander-Institut für Astronomie, Bonn, Germany
C. Henkel
Affiliation:
Max-Planck-Institut für Radioastronomie, Bonn, Germany
K. M. Menten
Affiliation:
Max-Planck-Institut für Radioastronomie, Bonn, Germany
A. Weiss
Affiliation:
Max-Planck-Institut für Radioastronomie, Bonn, Germany
M. S. Yun
Affiliation:
Department of Astronomy, University of Massachusetts, Amherst, MA, USA
N. Z. Scoville
Affiliation:
Astronomy Department, California Institute of Technology, Pasadena, CA, USA
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Abstract

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Molecular gas has now been detected in 15 z>2 QSOs. These detections are commonly obtained by observing high–J CO transitions due to their relatively high peak fluxes and observing frequencies in the millimeter atmospheric windows. However, only observations of the CO ground-state transition, CO(1–0), have the potential to trace the molecular gas at lower excitations, which may give a better estimate of the total molecular gas mass of high–z QSOs. Here we present first z>4 CO(1–0) observations obtained with the NRAO Green Bank Telescope and the MPIfR Effelsberg telescope (Riechers et al. 2006). With these two 100m telescopes, we detect the CO(1–0) transition in the high–redshift QSOs BR 1202-0725 (z = 4.7), PSS J2322+1944 (z = 4.1), and APM 08279+5255 (z = 3.9). We find that the CO/FIR luminosity ratios of these high-z sources follow the same trend as seen for low-z galaxies. Utilizing large velocity gradient (LVG) models based on previous results for higher–J CO transitions, we derive that all CO emission can be described by a single gas component and that all molecular gas appears to be concentrated in a compact nuclear region. We thus find no evidence for luminous, extended CO(1–0) components in the molecular gas reservoirs around our target quasars.

Keywords

cosmology: observationsgalaxies: ISMgalaxies: high-redshiftgalaxies: formationgalaxies: starburstgalaxies: active
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S235: Galaxy Evolution Across the Hubble Time , August 2006 , pp. 423
Copyright
Copyright © International Astronomical Union 2007

References

Riechers, D. A., Walter, F., Carilli, C. L. 2006, ApJ in press (astro-ph/0606422)Google Scholar