GMASS ultradeep spectroscopy of galaxies at z ~ 2

Aims. The properties of dust attenuation at rest-frame UV wavelengths are inferred from very high-quality FORS 2 spectra of 78 galaxies from the GMASS survey at redshift $1 < z < 2.5$. These objects complement a previously investigated sample of 108 UV-luminous, intermediate-mass (i.e., with stellar masses ~$10^{10}{-}10^{11}~M_{\sun}$) galaxies at similar redshifts, selected from the FDF spectroscopic survey, the K20 survey, and the GDDS. Detection of the broad absorption feature centred on about 2175 Å (“UV bump”) implies that the average UV extinction curve of a galaxy more closely resembles that of the Milky Way (MW) or the Large Magellanic Cloud (LMC), and differs from that of the Small Magellanic Cloud (SMC).