The ultraviolet properties of Luminous Infrared Galaxies at z ~ 0.7: is there any evolution in their dust attenuation?

TL;DR

This study investigates the evolution of dust attenuation in luminous infrared galaxies at z~0.7, finding a slight decrease in dust attenuation compared to local galaxies, which aligns with the observed increase in TIR to FUV luminosity density ratio over time.

Contribution

It provides new measurements of dust attenuation in LIRGs at z~0.7 and compares these with local counterparts, highlighting a smaller decrease than previously reported for UV-selected bright galaxies.

Findings

LIRGs at z=0.7 show a broader range of L(TIR)/L(FUV) ratios.

Mean dust attenuation at FUV is ~0.5 mag lower at z=0.7 than locally.

The decrease in dust attenuation is consistent with the increase in luminosity density ratio over redshift.

Abstract

The TIR and FUV luminosity functions of galaxies and the related luminosity densities rho(TIR) and rho(FUV) are known to evolve from z=0 to z~1 but with a different rate: the galaxy populations appear brighter in the past at both wavelengths but the evolution in TIR is larger than in FUV. It leads to an increase of the ratio of TIR to FUV luminosity densities rho(TIR)/rho(FUV) which can be interpreted as a global increase of the dust attenuation from z=0 to z~1. Our aim is to understand the origin of this increase. We focus on infrared galaxies with L(TIR>10^{11} Lsun at z~0.7 observed by SPITZER/MIPS and we measure their UV emission at 2310 A from GALEX. These Luminous InfraRed Galaxies (LIRGs) represent the bulk of the TIR luminosity density at intermediate redshift. Some evolution of L(TIR)/L(FUV) and therefore of dust attenuation is found for these galaxies: LIRGs at z=0.7 span a larger range of L(TIR)/L(FUV) ratios than at z=0 and their mean dust attenuation at FUV is found ~0.5 mag lower than for their local counterparts. The decrease of dust attenuation is found lower than that reported in other studies for bright galaxies selected in UV rest-frame at z=1 and 2. From a semi-quantitative analysis we find that the slight decrease of dust attenuation for LIRGs at z=0.7 remains consistent with the increase of rho(TIR)/rho(FUV) with redshift.