Large-scale magnetic field structure of NGC 3627 based on magnetic
  vector map
  We analyzed the data of Stokes $I$, $Q$, and $U$ in C- and X-bands and
investigated the large-scale magnetic field structure of NGC 3627. The
polarization intensity and angle in each band were derived using Stokes $Q$ and
$U$ maps. The rotation measure was calculated using the polarization-angle
maps. Moreover, the magnetic field strength was calculated by assuming energy
equipartition with the cosmic ray electrons. The structure of the magnetic
field was well aligned with the spiral arms, which were consistent with those
in the former studies. We applied the magnetic vector reconstruction method to
NGC 3627 to derive a magnetic vector map, which showed that northern and
southern disks were dominant with inward and outward magnetic vectors,
respectively. Furthermore, we discussed the large-scale structure of the
magnetic field in NGC 3627 and observed that the structure is bi-symmetric
spiral in nature, and that the number of magnetic field mode is $ m_{\rm B} = 1
$ in outer region of galaxy. In addition, NGC 3627 has a mode of two spiral
arms that were clearly visible in an optical image. The ratio of the mode of
spiral arms to that of magnetic field is 2:1. In terms of NGC 3627, the
large-scale magnetic field may be generated via the parametric resonance
induced by the gravitational potential of the spiral arms.
