a1 Institute of Astronomy, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan
a2 Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
a3 Astronomical Institute, Graduate School of Science, Tohoku University, Aramaki, Aoba, Sendai 980-8578, Japan
a4 Institute of Space and Astronautical Sciences, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510, Japan
a5 Gunma Astronomical Observatory, 6860-86 Nakayama, Takayama, Agatsuma, Gunma 377-0702, Japan
Faint submillimeter sources detected with JCMT/SCUBA have faced an identification problem due to their broad beam profiles. Here we propose a new method to identify these sources at the mid-infrared utilizing a finer point spread function. ISOCAM has provided us a very deep 6.7 μm image of the Hawaii Deep Field SSA13. For all three 850 μm sources in this field, we have found their 6.7 μm counterparts. All of them have been identified with interacting galaxy pairs at the optical. Two of the pairs are very faint and red (I>24, I - K > 4), one of the two has the hard X-ray detection with Chandra. Assuming an Arp 220 SED, we have found a typical redshift of z ~ 2. This requires that the sources should be a few times more luminous than Arp 220. It appears that extremely high star formation rates are occurring in galaxies at high redshift with massive stellar contents already in place.
(Online publication September 25 2002)