GOODS-Herschel: dust attenuation properties of UV selected high redshift galaxies

Abstract

Context. Dust attenuation in galaxies is poorly known, especially at high redshift. And yet the amount of dust attenuation is a key parameter to deduce accurate star formation rates from ultraviolet (UV) rest-frame measurements. The wavelength dependence of the dust attenuation is also of fundamental importance to interpret the observed spectral energy distributions (SEDs) and to derive photometric redshifts or physical properties of galaxies. Aims. We want to study dust attenuation at UV wavelengths at high redshift, where the UV is redshifted to the observed visible light wavelength range. In particular, we search for a UV bump and related implications for dust attenuation determinations. Methods. We use photometric data in the Chandra Deep Field South (CDFS), obtained in intermediate and broad band filters by the MUSYC project, to sample the UV rest-frame of 751 galaxies with 0.95 < z < 2.2. When available, infrared (IR) Herschel/PACS data from the GOODS-Herschel project, coupled with Spitzer/MIPS measurements, are used to estimate the dust emission and to constrain dust attenuation. The SED of each source is fit using the CIGALE code. The amount of dust attenuation and the characteristics of the dust attenuation curve are obtained as outputs of the SED fitting process, together with other physical parameters linked to the star formation history. Results. The global amount of dust attenuation at UV wavelengths is found to increase with stellar mass and to decrease as UV luminosity increases. A UV bump at 2175 Å is securely detected in 20% of the galaxies, and the mean amplitude of the bump for the sample is similar to that observed in the extinction curve of the LMC supershell region. This amplitude is found to be lower in galaxies with very high specific star formation rates, and 90% of the galaxies exhibiting a secure bump are at z < 1.5. The attenuation curve is confirmed to be steeper than that of local starburst galaxies for 20% of the galaxies. The large dispersion found for these two parameters describing the attenuation law is likely to reflect a wide diversity of attenuation laws among galaxies. The relations between dust attenuation, IR-to-UV flux ratio, and the slope of the UV continuum are derived for the mean attenuation curve found for our sample. Deviations from the average trends are found to correlate with the age of the young stellar population and the shape of the attenuation curve.

Quasar 2175 Å dust absorbers – II. Correlation analysis and relationship with other absorption line systems

“…The median stellar mass is comparable with that of the UV selected starforming galaxies in a similar redshift range by Buat et al (2012) where they find that the 2175Å bump is securely detected in 20% of these UV selected galaxies. Unlike most DLA host galaxies, which have been very difficult to detect in emission, the host galaxies of 2DAs are expected to be detected relatively easier.…”

Dusty star-forming galaxies at high redshift

“…Dunne et al, 2011;Buat et al, 2012;Magdis et al, 2012b) or specific starformation rate, sS FR (Santini et al, 2013). These works assume that the gas-to-dust mass ratio varies with metallicity and can be used to constrain gas fractions on and off the star forming main sequence.…”

Ultraviolet to infrared emission ofz> 1 galaxies: Can we derive reliable star formation rates and stellar masses?

“…2, with a particular attention paid to the sampling of the rest-frame UV continuum emission using a large number of intermediate band filters. These filters have been proven to be very effective in measuring photometric redshifts (Ilbert et al 2009;Benitez et al 2009;Cardamone et al 2010) as well as in characterising the dust attenuation (Buat et al , 2012 but, to our knowledge, their influence in retrieving physical parameters has not been studied yet. The fitting process, based on our modelling code, CIGALE (Noll et al 2009), is presented in Sect.…”