Astronomy & Astrophysics

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Issue		A&A Volume 440, Number 2, September III 2005
Page(s)		L17 - L20
Section		Letters
DOI		10.1051/0004-6361:200500158

A&A 440, L17-L20 (2005)
DOI: 10.1051/0004-6361:200500158

Letter

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

T. T. Takeuchi, V. Buat and D. Burgarella

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 z=0 to z=1 is discussed by using the luminosity functions (LFs) of both wavelengths. The FUV LF ( $z=0\mbox1$ ) 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- $\mu$ m LF for the local universe and the Spitzer 15- $\mu$ m 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 $\rho_{\rm dust}/\rho_{\rm FUV}$ increases toward higher-z, from $\sim$ 4 (local) to $\sim$ 15 ( $z\simeq 1$ ). It is also shown that more than $70\%$ of the star formation activity in the universe is obscured by dust at $0.5 \la z \la 1.2$ .

Key words: dust, extinction -- galaxies: evolution -- galaxies: luminosity function -- infrared: galaxies -- ultraviolet: galaxies

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