Magnetic Fields Structures and Turbulent Components in the Star Forming
  Molecular Clouds OMC-2 and OMC-3
  The SCUBA polarized 850 microns thermal emission data of the region OMC-2 in
Orion A are added to and homogeneously reduced with data already available in
the region OMC-3. The data set shows that OMC-2 is a region generally less
polarized than OMC-3. Where coincident, most of the 850 microns polarization
pattern is similar to that measured in 350 microns polarization data. Only 850
microns polarimetry data have been obtained in and around MMS7, FIR1 & FIR2,
and in the region south of FIR6. A realignment of the polarization vectors with
the filament can be seen near FIR1 in the region south of OMC-3. An analysis
shows that the energy injected by CO outflows and H2 jets associated to OMC-2
and OMC-3 does not appear to alter the polarization patterns at a scale of the
14'' resolution beam. A second order structure function analysis of the
polarization position angles shows that OMC-2 is a more turbulent region than
OMC-3. OMC-3 appears to be a clear case of a magnetically dominated region with
respect to the turbulence. However for OMC-2 it is not clear that this is the
case. A more in-depth analysis of five regions displayed along OMC-2/3
indicates a decrease of the mean polarization degree and an increase of the
turbulent angular dispersion from north to south. A statistical analysis
suggests the presence of two depolarization regimes in our maps. One regime
including the effects of the cores, the other one excluding it.
