Decarli, R. and Walter, F. and Aravena, M. and Carilli, C. and Bouwens, R. and da Cunha, E. and Daddi, E. and Ivison, R.J. and Popping, G. and Riechers, D. and Smail, I.R. and Swinbank, M. and Weiss, A. and Anguita, T. and Assef, R.J. and Bauer, F.E. and Bell, E.F. and Bertoldi, F. and Chapman, S. and Colina, L. and Cortes, P.C. and Cox, P. and Dickinson, M. and Elbaz, D. and Gónzalez-López, J. and Ibar, E. and Infante, L. and Hodge, J. and Karim, A. and Le Fevre, O. and Magnelli, B. and Neri, R. and Oesch, P. and Ota, K. and Rix, H.-W. and Sargent, M. and Sheth, K. and van der Wel, A. and van der Werf, P. and Wagg, J. (2016) 'ALMA Spectroscopic Survey in the Hubble Ultra Deep Field : CO luminosity functions and the evolution of the cosmic density of molecular gas.', Astrophysical journal., 833 (1). p. 69.
In this paper we use ASPECS, the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field in band 3 and band 6, to place blind constraints on the CO luminosity function and the evolution of the cosmic molecular gas density as a function of redshift up to z ~ 4.5. This study is based on galaxies that have been selected solely through their CO emission and not through any other property. In all of the redshift bins the ASPECS measurements reach the predicted "knee" of the CO luminosity function (around 5 × 109 K km s−1 pc2). We find clear evidence of an evolution in the CO luminosity function with respect to z ~ 0, with more CO-luminous galaxies present at z ~ 2. The observed galaxies at z ~ 2 also appear more gas-rich than predicted by recent semi-analytical models. The comoving cosmic molecular gas density within galaxies as a function of redshift shows a drop by a factor of 3–10 from z ~ 2 to z ~ 0 (with significant error bars), and possibly a decline at z > 3. This trend is similar to the observed evolution of the cosmic star formation rate density. The latter therefore appears to be at least partly driven by the increased availability of molecular gas reservoirs at the peak of cosmic star formation (z ~ 2).
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|Publisher Web site:||https://doi.org/10.3847/1538-4357/833/1/69|
|Publisher statement:||© 2016. The American Astronomical Society. All rights reserved.|
|Date accepted:||07 September 2016|
|Date deposited:||09 March 2017|
|Date of first online publication:||08 December 2016|
|Date first made open access:||09 March 2017|
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