Identification of Sources in MAMBO (1.2 mm) Deep Fields

Helmut Dannerbauer
Max-Planck-Institute for Space Physics
Garching, Germany

We have used the IRAM Plateau de Bure mm interferometer to locate with
subarcsecond accuracy the dust emission of three of the brightest 1.2 mm
sources in the NTT Deep Field (NDF) selected from our 1.2 mm MAMBO survey
at the IRAM 30 m telescope. We combine these results with deep B to K
imaging and VLA interferometry. Strikingly, none of the three accurately
located millimetre galaxies MMJ120546-0741.5, MMJ120539-0745.4, and
MMJ120517-0743.1 has a K-band counterpart down to the faint limit of
Ks > 21.9. This implies that these three galaxies are either extremely
obscured and/or are at very high redshift (z > =4).
Combining our results with similarly reliable identifications from the
literature, a first general picture emerges: at current sensitivities,
about roughly equal fractions of the population are (1) detected in the
optical and near-IR; (2) detected only in the near-IR, implying
extremely red colors; and (3) undetected even in deep near-IR imaging
(K > 22)