2011ApJ...730L..19G -
Astrophys. J., 730, L19 (2011/April-1)
On the evolution of the molecular gas fraction of star-forming galaxies.
GEACH J.E., SMAIL I., MORAN S.M., MacARTHUR L.A., LAGOS C.D.P. and EDGE A.C.
Abstract (from CDS):
We present IRAM Plateau de Bure interferometric detections of CO (J = 1 ⟶ 0) emission from a 24 µm-selected sample of star-forming galaxies at z = 0.4. The galaxies have polycyclic aromatic hydrocarbon 7.7 µm-derived star formation rates of SFR ∼30-60 M☉/yr and stellar masses M{sstarf}∼ 1011 M☉. The CO (J = 1 ⟶ 0) luminosities of the galaxies imply that the disks still contain a large reservoir of molecular gas, contributing ∼20% of the baryonic mass, but have star formation "efficiencies" similar to local quiescent disks and gas-dominated disks at z ∼ 1.5-2. We reveal evidence that the average molecular gas fraction has undergone strong evolution since z ∼ 2, with fgas∝ (1 + z)∼2±0.5. The evolution of fgas encodes fundamental information about the relative depletion/replenishment of molecular fuel in galaxies and is expected to be a strong function of halo mass. We show that the latest predictions for the evolution of the molecular gas fraction in semi-analytic models of galaxy formation within a ΛCDM universe are supported by these new observations.
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Journal keyword(s):
cosmology: observations - galaxies: evolution
Simbad objects:
11
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