HAWC+/SOFIA Multiwavelength Polarimetric Observations of OMC-1
  We report new polarimetric and photometric maps of the massive star-forming
region OMC-1 using the HAWC+ instrument on the Stratospheric Observatory for
Infrared Astronomy (SOFIA). We present continuum polarimetric and photometric
measurements of this region at 53, 89, 154, and 214 microns at angular
resolutions of 5.1, 7.9, 14.0, and 18.7 arcseconds for the four bands,
respectively. The photometric maps enable the computation of improved SEDs for
the region. We find that at the longer wavelengths, the inferred magnetic field
configuration matches the `hourglass' configuration seen in previous studies,
indicating magnetically-regulated star formation. The field morphology differs
at the shorter wavelengths. The magnetic field inferred at these wavelengths
traces the bipolar structure of the explosive Becklin-Neugebauer
(BN)/Kleinman-Low (KL) outflow emerging from OMC-1 behind the Orion Nebula.
Using statistical methods to estimate the field strength in the region, we find
that the explosion dominates the magnetic field near the center of the feature.
Farther out, the magnetic field is close to energetic equilibrium with the
ejecta and may be providing confinement to the explosion. The correlation
between polarization fraction and the local polarization angle dispersion
indicates that the depolarization as a function of unpolarized intensity is a
result of intrinsic field geometry as opposed to decreases in grain alignment
efficiency in denser regions.
