The ultraviolet-far-infrared energy budget of the gravitationally lensed Lyman break galaxy MS 1512-cB58

A 2 hr service-mode SCUBA observation of the gravitationally lensed Lyman break galaxy MS 1512-cB58 (hereafter cB58) resulted in a 3 sigma upper limit of 3.9 mJy at 850 mum. A comparison of this upper limit with values expected from rest-UV-optical measurements of extinction suggests that the dust temperature (T-d) and/or emissivity index (beta) in cB58 may be substantially higher than is seen in local galaxies, or that the attenuation curve in cB58 may be even gentler than the already quite mild SMC dust law. If dust temperature T-d and emissivity index beta in cB58 are similar to those seen in local IRAS- selected galaxies, then cB58's dust mass is M-d less than or similar to 10(7.7) M., and its star formation rate is SFR less than or similar to 10 M. yr(-1) (for q(0) = 0.1, H-0 = 75 km s(-1) Mpc(-1)). This SFR upper limit is lower than the star formation rate measured from H alpha, thus giving further support to the notion that (T-d, beta) values in cB58 are higher than those seen in local galaxies. It thus appears that our understanding of dust in this extensively studied Lyman break galaxy is poor, and observations at other wavelengths are needed to better understand dust at high redshift. Such observations can be provided by the upcoming SIRT F mission for which cB58's expected flux densities are calculated.