Data from: The Evolution of the Baryons Associated with Galaxies Averaged over Cosmic Time and Space

Full description

We combine the recent determination of the evolution of the cosmic density of molecular gas (H2) using deep, volumetric surveys, with previous estimates of the cosmic density of stellar mass, star formation rate and atomic gas (H i), to constrain the evolution of baryons associated with galaxies averaged over cosmic time and space. The cosmic H i and H2 densities are roughly equal at z ∼ 1.5. The H2 density then decreases by a factor 6-2+3 to today's value, whereas the H i density stays approximately constant. The stellar mass density is increasing continuously with time and surpasses that of the total gas density (H i and H2) at redshift z ∼ 1.5. The growth in stellar mass cannot be accounted for by the decrease in cosmic H2 density, necessitating significant accretion of additional gas onto galaxies. With the new H2 constraints, we postulate and put observational constraints on a two-step gas accretion process: (i) a net infall of ionized gas from the intergalactic/circumgalactic medium to refuel the extended H i reservoirs, and (ii) a net inflow of H i and subsequent conversion to H2 in the galaxy centers. Both the infall and inflow rate densities have decreased by almost an order of magnitude since z ∼ 2. Assuming that the current trends continue, the cosmic molecular gas density will further decrease by about a factor of two over the next 5 Gyr, the stellar mass will increase by approximately 10%, and cosmic star formation activity will decline steadily toward zero, as the gas infall and accretion shut down.

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External Organisations
Max Planck Institute for Astronomy; National Radio Astronomy Observatory; University of Cambridge; Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna; National Institute for Astrophysics; European Southern Observatory; State University of New Jersey; Rutgers - The State University of New Jersey, New Brunswick; Simons Foundation; Universidad Diego Portales; University of Bonn; Leiden University; Sorbonne Université; Cornell University; Durham University; Max Planck Institute for Radio Astronomy; Pontificia Universidad Católica de Chile; Instituto Milenio de Astrofísica; Space Science Institute; CNRS; Université Paul Sabatier Toulouse III; Atacama Large Millimeter/submillimeter Array; ComUE Paris-Saclay; Foundation for Research and Technology-Hellas; University of Chinese Academy of Sciences; Carnegie Institution of Washington; University of California Santa Barbara; Hiroshima University; University of Edinburgh; University of Geneva; University of Copenhagen; University of Sussex; SKA Organisation

Associated Persons
Fabian Walter (Creator); Chris Carilli (Creator); Marcel Neeleman (Creator); Roberto Decarli (Creator); Gergö Popping (Creator); Rachel S. Somerville (Creator); Manuel Aravena (Creator); Frank Bertoldi (Creator); Leindert Boogaard (Creator); Pierre Cox (Creator); Benjamin Magnelli (Creator); D. A. Riechers (Creator); Hans Walter Rix (Creator); Ian Smail (Creator); Axel Weiss (Creator); Roberto J. Assef (Creator); Franz Erik Bauer (Creator); Rychard Bouwens (Creator); Thierry Contini (Creator); Paulo C. Cortes (Creator); Emanuele Daddi (Creator); Tanio Díaz-Santos (Creator); Jorge González-López (Creator); Joseph Hennawi (Creator); Jacqueline A. Hodge (Creator); Hanae Inami (Creator); R. J. Ivison (Creator); P. A. Oesch (Creator); Mark T. Sargent (Creator); Paul van der Werf (Creator); Jeff Wagg (Creator); L. Y.Aaron Yung (Creator)