Interpreting the observed UV continuum slopes of high-redshift galaxies
  The observed UV continuum slope of star forming galaxies is strongly affected
by the presence of dust. Its observation is then a potentially valuable
diagnostic of dust attenuation, particularly at high-redshift where other
diagnostics are currently inaccesible. Interpreting the observed UV continuum
slope in the context of dust attenuation is often achieved assuming the
empirically calibrated Meurer et al. (1999) relation. Implicit in this relation
is the assumption of an intrinsic UV continuum slope ($\beta=-2.23$). However,
results from numerical simulations suggest that the intrinsic UV continuum
slopes of high-redshift star forming galaxies are bluer than this, and moreover
vary with redshift. Using values of the intrinsic slope predicted by numerical
models of galaxy formation combined with a Calzetti et al. (2000) reddening law
we infer UV attenuations ($A_{1500}$) $0.35-0.5\,{\rm mag}$ ($A_{V}$:
$0.14-0.2\,{\rm mag}$ assuming Calzetti et al. 2000) greater than simply
assuming the Meurer relation. This has significant implications for the
inferred amount of dust attenuation at very-high ($z\approx 7$) redshift given
current observational constraints on $\beta$, combined with the Meurer
relation, suggest dust attenuation to be virtually zero in all but the most
luminous systems.
