The Canada-France Redshift Survey: The Luminosity Density and Star Formation History of the Universe to [ITAL]z[/ITAL] ∼ 1

Abstract

The comoving luminosity density of the universe, (λ), is estimated from the Canada-France Redshift Survey (CFRS) faint galaxy sample in three wave bands (2800 Å, 4400 Å, and 1 μm) over the redshift range 0 < z < 1. In all three wave bands, increases markedly with redshift. For a ( q 0 = 0.5, Ω = 1.0) cosmological model, the comoving luminosity density increases as (1 + z ) 2.1 ± 0.5 at 1 μm, as (1 + z ) 2.7 ± 0.5 at 4400 Å, and as (1 + z ) 3.9 ± 0.75 at 2800 Å, these exponents being reduced by 0.43 and 1.12 for (0.05, 0.1) and (-0.85, 0.1) cosmological models, respectively. The (λ)-τ relation can be reasonably well modeled by an actively evolving stellar population with a Salpeter initial mass function (IMF) extending to 125 M ☉ , and a star formation rate declining as τ -2.5 with a turn-on of star formation at early epochs. A Scalo IMF extending to the same mass limit produces too many long-lived low-mass stars. This rapid evolution of the star formation rate and comoving luminosity density of the universe is in good agreement with the conclusions of Pei & Fall from their analysis of the evolving metallicity of the universe. One consequence of this evolution is that the physical luminosity density at short wavelengths has probably declined by 2 orders of magnitude since z ~ 1.