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Paper: CO(10) Emission from Quasar Host Galaxies Beyond Redshift 4
Volume: 375, From Z-Machines to ALMA: (Sub)Millimeter Spectroscopy of Galaxies
Page: 148
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.
Abstract: Molecular gas has now been detected in 15 z > 2 QSOs through observations of high-J CO transitions using millimeter interferometers. Observations of the CO ground-state transition CO(10), however, have the potential to trace the molecular gas at lower excitations, which may give a better estimate of the total molecular gas content of high-z QSOs. Here we present the first z > 4 CO(10) observations obtained with the NRAO Green Bank Telescope (GBT) and the MPIfR Effelsberg telescope. Utilizing the K band receivers of these two 100m radio telescopes, we detect the CO(10) transition in the high-redshift QSOs BR1202−0725 (z = 4.7), PSS J2322+1944 (z = 4.1), and APM08279+5255 (z = 3.9). From LVG models based on our observations out to z = 4.7, we derive that the CO emission from all observed transitions can be described by a single gas component, and that all molecular gas appears to be concentrated in a compact nuclear region. The spectral capabilities of the GBT (1 200MHz in high-resolution mode, 2 800MHz in high-bandwidth mode) allow us to cover velocity ranges of up to 22, 000 kms−1, or Δz/z = 0.09 at z = 4, which will be imperative for future high-z studies in galaxies with known strong dust continuum but poorly constrained redshift. This is a first step towards observations with future z-machines.
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