The ultraviolet properties of luminous infrared galaxies at z ~ 0.7

Is there any evolution in their dust attenuation?

¹ Observatoire Astronomique Marseille Provence, Laboratoire d'Astrophysique de Marseille, BP 8, 133761 Marseille Cedex 12, France e-mail: veronique.buat@oamp.fr
² Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
³ Spitzer fellow, Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
⁴ Astronomical Institute, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai 980–8578, Japan
⁵ Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464–8601, Japan
⁶ Instituto de Astrofísica de Andalucía,CSIC, 18008 Granada, Spain
⁷ California Institute of Technology, MC 405-47, 1200 East California Boulevard, Pasadena, CA 91125, USA

Received: 3 November 2006
Accepted: 19 February 2007

Abstract

Aims.The total infrared (TIR: 8-1000 μm) and far-ultraviolet (FUV: ~1500 Å) luminosity functions of galaxies and the related luminosity densities and are known to evolve at differemt rates from to z ~1: the galaxy populations appear to be brighter in the past at both wavelengths, but the evolution in the TIR is larger than in the FUV. This leads to an increase of the ratio of TIR to FUV luminosity densities which can be interpreted as a global increase of the dust attenuation from to z ~ 1. Our aim is to understand the origin of this increase: is it entirely due to a variation of the dust attenuation with the luminosity of the galaxies as seen as or are properties of galaxies evolving with the redshift?

Methods.We focus on infrared galaxies more luminous than L_TIR = 10¹¹  at z ~ 0.7 observed by SPITZER/MIPS and we measure their ultraviolet emission at 2310 Å from GALEX images. These Luminous InfraRed Galaxies (LIRGs) represent the bulk of the TIR luminosity density at intermediate redshift. The analysis of the ratio of TIR to FUV (rest-frame) luminosity enables us to discuss and compare their dust attenuation to that of galaxies of similar infrared luminosity selected in the same way in the nearby universe

Results.Some evolution of and therefore of dust attenuation is found: LIRGs at .7 span a larger range of  ratios than at and their mean dust attenuation at FUV wavelengths is found to be ~ 0.5 mag lower than for their local counterparts. The decrease of dust attenuation is found to be less than that reported in other studies for bright galaxies selected in UV rest-frame at and 2. A semi-quantitative analysis accounts for the general increase of dust attenuation with the bolometric luminosity of galaxies: it is found that the slight decrease of dust attenuation for LIRGs at .7 remains consistent with the increase of with redshift.