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Molecular gas in intermediate-redshift ultraluminous infrared galaxies.
- Source :
-
Monthly Notices of the Royal Astronomical Society . Oct2011, Vol. 416 Issue 4, p2600-2606. 7p. - Publication Year :
- 2011
-
Abstract
- ABSTRACT We report on the results of observations in the CO(1-0) transition of a complete sample of Southern, intermediate-redshift ( z= 0.2-0.5) ultraluminous infrared galaxies (ULIRGs) using the Mopra 22-m telescope. The 11 ULIRGs with LFIR > 1012.5 L⊙ south of δ=−12° were observed with integration times that varied between 5 and 24 h. Four marginal detections were obtained for individual targets in the sample. The 'stacked' spectrum of the entire sample yields a high significance, 10σ detection of the CO(1-0) transition at an average redshift of z= 0.38. The tightest correlation of LFIR and LCO for published low-redshift ULIRG samples ( z < 0.2) is obtained after normalization of both these measures to a fixed dust temperature. With this normalization the relationship is linear. The distribution of dust-to-molecular hydrogen gas mass displays a systematic increase in dust-to-gas mass with galaxy luminosity for low-redshift samples, but this ratio declines dramatically for intermediate-redshift ULIRGs down to values comparable to that of the Small Magellanic Cloud. The upper envelope to the distribution of ULIRG molecular mass as function of look-back time demonstrates a dramatic rise by almost an order of magnitude from the current epoch out to 5 Gyr. This increase in maximum ULIRG gas mass with look-back time is even more rapid than that of the star formation rate density. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00358711
- Volume :
- 416
- Issue :
- 4
- Database :
- Academic Search Index
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Publication Type :
- Academic Journal
- Accession number :
- 65551872
- Full Text :
- https://doi.org/10.1111/j.1365-2966.2011.19212.x