HerMES: Spectral Energy Distributions of Submillimeter Galaxies at z >4
  We present a study of the infrared properties for a sample of seven
spectroscopically confirmed submillimeter galaxies at $z>$4.0. By combining
ground-based near-infrared, Spitzer IRAC and MIPS, Herschel SPIRE, and
ground-based submillimeter/millimeter photometry, we construct their Spectral
Energy Distributions (SED) and a composite model to fit the SEDs. The model
includes a stellar emission component at $\lambda_{\rm rest} <$ 3.5$ \mu$m; a
hot dust component peaking at $\lambda_{rest} \sim$ 5$\,\mu$m; and cold dust
component which becomes significant for $\lambda_{\rm rest} >$ 50$\,\mu$m. Six
objects in the sample are detected at 250 and 350$ \mu$m. The dust temperatures
for the sources in this sample are in the range of 40$-$80 K, and their $L_{\rm
FIR}$ $\sim$ 10$^{13}$ L$_{\odot}$ qualifies them as Hyper$-$Luminous Infrared
Galaxies (HyperLIRGs). The mean FIR-radio index for this sample is around $< q
> = 2.2$ indicating no radio excess in their radio emission. Most sources in
the sample have 24$ \mu$m detections corresponding to a rest-frame 4.5$ \mu$m
luminosity of Log$_{10}$(L$_{4.5}$ / L$_{\odot}$) = 11 $\sim$ 11.5. Their
L$_{\rm 4.5}$/$L_{\rm FIR}$ ratios are very similar to those of starburst
dominated submillimeter galaxies at $z \sim$ 2. The $L_{\rm CO}-L_{\rm FIR}$
relation for this sample is consistent with that determined for local ULIRGs
and SMGs at $z \sim$ 2. We conclude that submillimeter galaxies at $z >$ 4 are
hotter and more luminous in the FIR, but otherwise very similar to those at $z
\sim$ 2. None of these sources show any sign of the strong QSO phase being
triggered.
