  We report on the detection of the [CII] 157.7 $\mu$m emission from the Lyman
break galaxy (LBG) MACS0416_Y1 at z = 8.3113, by using the Atacama Large
Millimeter/submillimeter Array (ALMA). The luminosity ratio of [OIII] 88 $\mu$m
(from previous campaigns) to [CII] is 9.31 $\pm$ 2.6, indicative of hard
interstellar radiation fields and/or a low covering fraction of
photo-dissociation regions. The emission of [CII] is cospatial to the 850
$\mu$m dust emission (90 $\mu$m rest-frame, from previous campaigns), however
the peak [CII] emission does not agree with the peak [OIII] emission,
suggesting that the lines originate from different conditions in the
interstellar medium. We fail to detect continuum emission at 1.5 mm (160 $\mu$m
rest-frame) down to 18 $\mu$Jy (3$\sigma$). This nondetection places a strong
limit on the dust spectrum, considering the 137 $\pm$ 26 $\mu$Jy continuum
emission at 850 $\mu$m. This suggests an unusually warm dust component (T $>$
80 K, 90% confidence limit), and/or a steep dust-emissivity index ($\beta_{\rm
dust}$ $>$ 2), compared to galaxy-wide dust emission found at lower redshifts
(typically T $\sim$ 30 - 50 K, $\beta_{\rm dust}$ $\sim$ 1 - 2). If such
temperatures are common, this would reduce the required dust mass and relax the
dust production problem at the highest redshifts. We therefore warn against the
use of only single-wavelength information to derive physical properties,
recommend a more thorough examination of dust temperatures in the early
Universe, and stress the need for instrumentation that probes the peak of warm
dust in the Epoch of Reionization.
