Near-infrared polarimetry of a normal spiral galaxy viewed through the
  Taurus Molecular Cloud Complex
  Few normal galaxies have been probed using near-infrared polarimetry, even
though it reveals magnetic fields in the cool interstellar medium better than
either optical or radio polarimetry. Deep H-band (1.6um) linear imaging
polarimetry toward Taurus serendipitously included the galaxy 2MASX
J04412715+2433110 with adequate sensitivity and resolution to map polarization
across nearly its full extent. The observations revealed the galaxy to be a
steeply inclined (~75 deg) disk type with a diameter, encompassing 90% of the
Petrosian flux, of 4.2 kpc at a distance of 53 Mpc. Because the sight line
passes through the Taurus Molecular Cloud complex, the foreground polarization
needed to be measured and removed. The foreground extinction Av of 2.00+/-0.10
mag and reddening E(H-K) of 0.125 +/- 0.009 mag were also assessed and removed,
based on analysis of 2MASS, UKIDSS, Spitzer, and WISE photometry using the
NICE, NICER, and RJCE methods. Corrected for the polarized foreground, the
galaxy polarization values range from zero to 3%. The polarizations are
dominated by a disk-parallel magnetic field geometry, especially to the
northeast, while either a vertical field or single scattering of bulge light
produces disk-normal polarizations to the southwest. The multi-kpc coherence of
the magnetic field revealed by the infrared polarimetry is in close agreement
with short wavelength radio synchrotron observations of edge-on galaxies,
indicating that both cool and warm interstellar media of disk galaxies may be
threaded by common magnetic fields.
