Letter to the Editor

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

Laboratoire d'Astrophysique de Marseille, Traverse du Siphon, BP 8, 13376 Marseille Cedex 12, France e-mail: [ tsutomu.takeuchi;veronique.buat;denis.burgarella] @oamp.fr

Received: 25 February 2005
Accepted: 20 July 2005

Abstract

The ratio between far-ultraviolet (FUV) and infrared (IR) luminosity densities from to is discussed by using the luminosity functions (LFs) of both wavelengths. The FUV LF () based on GALEX has been reported by (Arnouts et al. (2005, ApJ, 619, L43), whilst for the IR LF, we used the IRAS PSCz 60-μm LF for the local universe and the Spitzer 15-μm LF at higher-z as used by Le Floc'h et al. (2005, ApJ, in press). Both luminosity densities show a significant evolutionary trend, but the IR evolves much faster than the FUV. Consequently, the ratio increases toward higher-z, from ∼4 (local) to ∼15 (). It is also shown that more than of the star formation activity in the universe is obscured by dust at .