  We present the radio and X-ray properties of 1.2 mm MAMBO source candidates
in a 1600 sq. arcmin field centered on the Abell 2125 galaxy cluster at
z=0.247. The brightest, non-synchrotron mm source candidate in the field has a
photometric redshift, z = 3.93^+1.11_-0.80, and is not detected in a 31 ks
Chandra X-ray exposure. These findings are consistent with this object being an
extremely dusty and luminous starburst galaxy at high-redshift, possibly the
most luminous yet identified in any blank-field mm survey. The deep 1.4 GHz VLA
imaging identifies counterparts for 83% of the 29 mm source candidates
identified at >=4-sigma S(1.2mm) = 2.7 - 52.1 mJy, implying that the majority
of these objects are likely to lie at z <~ 3.5. The median mm-to-radio
wavelength photometric redshift of this radio-detected sample is z~2.2 (first
and third quartiles of 1.7 and 3.0), consistent with the median redshift
derived from optical spectroscopic surveys of the radio-detected subsample of
bright submm galaxies (S(850um) > 5 mJy). Three mm-selected quasars are
confirmed to be X-ray luminous in the high resolution Chandra imaging, while
another mm source candidate with potential multiple radio counterparts is also
detected in the X-ray regime. Both of these radio counterparts are positionally
consistent with the mm source candidate. One counterpart is associated with an
elliptical galaxy at z = 0.2425, but we believe that a second counterpart
associated with a fainter optical source likely gives rise to the mm emission
at z~1.
