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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 308594.0, MPI für Astronomie / Publikationen_mpia
CO(1-0) in z >~ 4 quasar fost galaxies: No evidence for extended molecular gas reservoirs
Authors:Riechers, D. A.; Walter, F.; Carilli, C. L.; Knudsen, K. K.; Lo, K. Y.; Benford, D. J.; Staguhn, J. G.; Hunter, T. R.; Bertoldi, F.; Henkel, C.; Menten, K. M.; Weiss, A.; Yun, M. S.; Scoville, N. Z.
Date of Publication (YYYY-MM-DD):2006
Journal Abbrev.:The Astrophysical Journal
Start Page:604
End Page:613
Audience:Not Specified
Abstract / Description:We present 12CO(J=1-->0) observations of the high-redshift quasi-stellar objects (QSOs) BR 1202-0725 (z=4.69), PSS J2322+1944 (z=4.12), and APM 08279+5255 (z=3.91) using the NRAO Green Bank Telescope (GBT) and the MPIfR Effelsberg 100 m telescope. We detect, for the first time, the CO ground-level transition in BR 1202-0725. For PSS J2322+1944 and APM 08279+5255, our observations result in line fluxes that are consistent with previous NRAO Very Large Array (VLA) observations, but they reveal the full line profiles. We report a typical lensing-corrected velocity-integrated intrinsic 12CO(J=1-->0) line luminosity of L'CO=5×1010 K km s-1 pc2 and a typical total H2 mass of M(H2)=4×1010 Msolar for the sources in our sample. The CO/FIR luminosity ratios of these high-z sources follow the same trend as seen for low-z galaxies, leading to a combined solution of logLFIR=(1.39+/-0.05)logLCO-1.76. It has previously been suggested that the molecular gas reservoirs in some quasar host galaxies may exhibit luminous, extended 12 CO(J=1-->0) components that are not observed in the higher J CO transitions. Using the line profiles and the total intensities of our observations and large velocity gradient (LVG) models based on previous results for higher J CO transitions, we derive that emission from all CO transitions is described well by a single gas component in which all molecular gas is concentrated in a compact nuclear region. Thus, our observations and models show no indication of a luminous extended, low surface brightness molecular gas component in any of the high-redshift QSOs in our sample. If such extended components exist, their contribution to the overall luminosity is limited to at most 30%.
Free Keywords:Cosmology: Observations; Galaxies: Active; Galaxies: Formation; Galaxies: High-Redshift; Galaxies: ISM; Galaxies: Starburst
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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