  Faint submillimeter sources detected with the Submillimeter Common-User
Bolometer Array on the James Clerk Maxwell Telescope have faced an
identification problem due to the telescope's broad beam profile. Here we
propose a new method to identify such submillimeter sources with a mid-infrared
image having a finer point spread function. The Infrared Space Observatory has
provided a very deep 6.7 um image of the Hawaii Deep Field SSA13. All three
faint 850 um sources in this field have their 6.7 um counterparts. They have
been identified with interacting galaxy pairs in optical images. These pairs
are also detected in the radio. Two of them are optically faint and very red
(I>24, I-K>4), one of which has a hard X-ray detection with the Chandra
satellite. As these observing properties are similar to those of local
ultraluminous infrared galaxies, their photometric redshifts are derived based
on submillimeter to mid-infrared flux ratios assuming a spectral energy
distribution (SED) of Arp220. Other photometric redshifts are obtained via
chi^2 minimization between the available photometry data and template SEDs.
Both estimates are in the range z=1-2, in good agreement with a spectroscopic
redshift and a millimetric one. The reconstructed Arp220 SEDs with these
redshift estimates are consistent with all the photometry data except Chandra's
hard X-ray detection. The sources would be a few times more luminous than
Arp220. With an assumption that AGN contributions are negligible, it appears
that extremely high star formation rates are occurring in galaxies at high
redshifts with massive stellar contents already in place.
