2013A&A...554L...3O

Lyman-break galaxies (LBGs) represent one of the kinds of star-forming galaxies that are found in the high-redshift universe. The detection of LBGs in the far-infrared (FIR) domain can provide very important clues on their dust attenuation and total star-formation rate (SFR), allowing a more detailed study than has been performed so far. In this work we explore the FIR emission of a sample of 16 LBGs at z∼3 in the GOODS-North and GOODS-South fields that are individually detected in PACS-100µm or PACS-160µm. These detections demonstrate the possibility of measuring the dust emission of LBGs at high redshift. We find that PACS-detected LBGs at z∼3 are highly obscured galaxies which belong to the ultra-luminous or hyper-luminous IR galaxy class. Their total SFR cannot be recovered with the dust attenuation factors obtained from their UV continuum slope or their SED-derived dust attenuation employing [Bruzual & Charlot, 2003MNRAS.344.1000B] templates. Both methods underestimate the results for most of the galaxies. Comparing with a sample of PACS-detected LBGs at z∼1, we find evidence that the FIR emission of LBGs might have changed with redshift, in the sense that the dustiest LBGs found at z∼3 have more prominent FIR emission, are dustier for a given UV slope, and have higher SFR for a given stellar mass than the dustiest LBGs found at z∼1.