Dust attenuation in the rest-frame ultraviolet: constraints from star-forming galaxies at z ∼ 1

A novel technique is employed for estimating attenuation curves in galaxies where only photometry and spectroscopic redshifts are available. This technique provides a powerful measure of particular extinction features such as the UV bump at 2175 angstrom, which has been observed in environments ranging from the MilkyWay to high-redshift star-forming galaxies. Knowledge of the typical strength of the UV bump as a function of environment and redshift is crucial for converting rest-frame UV flux into star formation rates. The UV bump will impart a unique signature as it moves through various filters due to redshifting; its presence can therefore be disentangled from other stellar population effects. The utility of this technique is demonstrated with a large sample of galaxies drawn from the DEEP2 Galaxy Redshift Survey. The observed B - R colour of star-forming galaxies at 0.6 < z < 1.4 disfavours the presence of a UV bump as strong as observed in the Milky Way, and instead favours rest-frame UV (1800 angstrom < lambda < 3000 angstrom) attenuation curves similar to the Milky Way without a UV bump, a power law with index delta = - 0.7, or a form advocated by Calzetti and collaborators. Stronger constraints on the strength of the UV bump in galaxies can be achieved if independent constraints on the V-band optical depth are available.