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Monthly Notices of the Royal Astronomical Society


We report the detection of CO(1–0) line emission from seven Planck and Herschel selected hyper luminous (LIR(8−1000μm) > 1013 L⊙) infrared galaxies with the Green Bank Telescope (GBT). CO(1–0) measurements are a vital tool to trace the bulk molecular gas mass across all redshifts. Our results place tight constraints on the total gas content of these most apparently luminous high-z star-forming galaxies (apparent IR luminosities of LIR > 1013 − 14 L⊙), while we confirm their predetermined redshifts measured using the Large Millimeter Telescope, LMT (zCO = 1.33–3.26). The CO(1–0) lines show similar profiles as compared to Jup = 2–4 transitions previously observed with the LMT. We report enhanced infrared to CO line lu- minosity ratios of ⟨LIR/L′CO(1−0)⟩ = 110 ± 22 L⊙(K km s−1 pc−2)−1 compared to normal star-forming galaxies, yet similar to those of well-studied IR-luminous galaxies at high-z. We find average brightness temperature ratios of ⟨ r21 ⟩ = 0.93 (2 sources), ⟨ r31 ⟩ = 0.34 (5 sources), and ⟨r41⟩ = 0.18 (1 source). The r31 and r41 values are roughly half the average values for SMGs. We estimate the total gas mass content as μMH2 = (0.9−27.2) × 1011(αCO/0.8) M⊙, where μ is the magnification factor and αCO is the CO line luminosity to molecular hydrogen gas mass conversion factor. The rapid gas depletion times, ⟨τdepl⟩ = 80 Myr, reveal vigorous starburst activity, and contrast the Gyr depletion time-scales observed in local, normal star-forming galaxies.


galaxies: high-redshift, galaxies: ISM, galaxies: starburst





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© 2017 The Author(s)


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