Outflows, cores and magnetic field orientations in W43-MM1 as seen by
  ALMA
  It has been proposed that the magnetic field, pervasive in the ISM, plays an
important role in the process of massive star formation. To better understand
its impact at the pre and protostellar stages, high-angular resolution
observations of polarized dust emission toward a large sample of massive dense
cores are needed. To this end, we used the Atacama Large Millimeter Array in
Band 6 (1.3 mm) in full polarization mode to map the polarized emission from
dust grains at a physical scale of $\sim$2700 au in the massive protocluster
W43-MM1. We used these data to measure the orientation of the magnetic field at
the core scale. Then, we examined the relative orientations of the core-scale
magnetic field, of the protostellar outflows determined from CO molecular line
emission, and of the major axis of the dense cores determined from 2D Gaussian
fit in the continuum emission. We found that the orientation of the dense cores
is not random with respect to the magnetic field. Instead, the dense cores are
compatible with being oriented 20-50$^\deg$ with respect to the magnetic field.
The outflows could be oriented 50-70$^\deg$ with respect to the magnetic field,
or randomly oriented with respect to the magnetic field, similar to current
results in low-mass star-forming regions. In conclusion, the observed alignment
of the position angle of the cores with respect to the magnetic field lines
shows that the magnetic field is well coupled with the dense material; however,
the 20-50$^\deg$ preferential orientation contradicts the predictions of the
magnetically-controlled core-collapse models. The potential correlation of the
outflow directions with respect to the magnetic field suggests that, in some
cases, the magnetic field is strong enough to control the angular momentum
distribution from the core scale down to the inner part of the circumstellar
disks where outflows are triggered.
