2010MNRAS.407L..94S

We have carried out 870-µm observations in the J1040.7-1155 field, known to host an overdensity of Lyman break galaxies at z = 5.16 ± 0.05. We do not detect any individual source at the S_870µm= 3.0 mJy/beam (2σ) level. A stack of nine spectroscopically confirmed z > 5 galaxies also yields a non-detection, constraining the submillimetre flux from a typical galaxy at this redshift to S_870µm< 0.85mJy, which corresponds to a mass limit M_dust< 1.2x10⁸M_☉(2σ). This limits the mass of thermal dust in distant Lyman break galaxies to less than one-tenth of their typical stellar mass. We see no evidence for strong submillimetre galaxies associated with the ultraviolet-selected galaxy overdensity, but cannot rule out the presence of fainter, less massive sources.