A Lack of Resolved Near-Infrared Polarization Across the Face of M51
  The galaxy M51 was observed using the Mimir instrument on the Perkins
telescope to constrain the resolved H-band (1.6 $\mu$m) polarization across the
galaxy. These observations place an upper limit of $P_H<0.05%$ on the $H$-band
polarization across the face of M51, at 0.6 arcsecond pixel sampling. Even with
smoothing to coarser angular resolutions, to reduce polarization uncertainty,
the $H$-band polarization remains undetected. The polarization upper limit at
$H$-band, when combined with previous resolved optical polarimetry, rules out a
Serkowski-like polarization dependence on wavelength. Other polarization
mechanisms cannot account for the observed polarization ratio ($P_H/P{VRI}
\lesssim 0.05$) across the face of M51.
