The evolution of the ultraviolet and infrared luminosity densities in the universe at 0<z<1

Abstract

The ratio between far-ultraviolet (FUV) and infrared (IR) luminosity densities from z=0 to z=1 is discussed by using the luminosity functions (LFs) of both wavelengths. The FUV LF (z=0-1) based on GALEX has been reported by Arnouts et al. (2005), whilst for the IR LF, we used the IRAS PSCz 60-um LF for the local universe and the Spitzer 15-um LF at higher-z as used by Le Floch et al. (2005). Both luminosity densities show a significant evolutionary trend, but the IR evolves much faster than the FUV. Consequently, the ratio $ρ_{dust}/ρ_{FUV}$ increases toward higher-z, from 4 (local) to 15 (z = 1). It is also shown that more than 70% of the star formation activity in the universe is obscured by dust at 0.5 < z < 1.2.

5 pages, 3 figures, accepted for publication in A&A Letters