Magnetic field structure of OMC-3 in the far infrared revealed by
  SOFIA/HAWC+
  We report the SOFIA/HAWC+ band D (154$\,\mu$m) and E (214$\,\mu$m)
polarimetric observations of the filamentary structure OMC-3 that is part of
the Orion molecular cloud. The polarization pattern is uniform for both bands
and parallel to the filament structure. The polarization degree decreases
toward regions with high intensity for both bands, revealing a so called
"polarization hole." We identified an optical depth effect in which polarized
emission and extinction act as counteracting mechanisms as a potential
contributor to this phenomenon. Assuming that the detected polarization is
caused by the emission of magnetically aligned non-spherical dust grains, the
inferred magnetic field is uniform and oriented perpendicular to the filament.
The magnetic field strength derived from the polarization patterns at
154$\,\mu$m and 214$\,\mu$m amounts to 202$\,\mu$G and 261$\,\mu$G,
respectively. The derived magnetic field direction is consistent with that
derived from previous polarimetric observations in the far infrared and
submillimeter (submm) wavelength range. Investigating the far-infrared
polarization spectrum derived from the SOFIA/HAWC+ observations, we do not find
a clear correlation between the polarization spectrum and cloud properties,
namely, the column density, $N(H_2$), and temperature, $T$.
