ALMA observations reveal no preferred outflow--filament and
  outflow--magnetic field orientations
  We present a statistical study on the orientation of outflows with respect to
large-scale filaments and the magnetic fields. Although filaments are widely
observed toward Galactic star-forming regions, the exact role of filaments in
star formation is unclear. Studies toward low-mass star-forming regions
revealed both preferred and random orientation of outflows respective to the
filament long-axes, while outflows in massive star-forming regions mostly
oriented perpendicular to the host filaments, and parallel to the magnetic
fields at similar physical scales. Here, we explore outflows in a sample of 11
protoclusters in HII regions, a more evolved stage compared to IRDCs, using
ALMA CO (3-2) line observations. We identify a total of 105 outflow lobes in
these protoclusters. Among the 11 targets, 7 are embedded within parsec-scale
filamentary structures detected in $^{13}$CO line and 870 $\mu m$ continuum
emissions. The angles between outflow axes and corresponding filaments
($\gamma_\mathrm{Fil}$) do not show any hint of preferred orientations (i.e.,
orthogonal or parallel as inferred in numerical models) with respect to the
position angle of the filaments. Identified outflow lobes are also not
correlated with the magnetic fields and Galactic plane position angles.
Outflows associated with filaments aligned along the large-scale magnetic
fields are also randomly orientated. Our study presents the first statistical
results of outflow orientation respective to large-scale filaments and magnetic
fields in evolved massive star-forming regions. The random distribution
suggests a lack of alignment of outflows with filaments, which may be a result
of the evolutionary stage of the clusters.
