A New Optical Polarization Catalog for the Small Magellanic Cloud: The
  Magnetic Field Structure
  We present a new optical polarimetric catalog for the Small Magellanic Cloud
(SMC). It contains a total of 7207 stars, located in the Northeast (NE) and
Wing sections of the SMC and part of the Magellanic Bridge. This new catalog is
a significant improvement compared to previous polarimetric catalogs for the
SMC. We used it to study the sky-projected interstellar magnetic field
structure of the SMC. Three trends were observed for the ordered magnetic field
direction at position angles of $(65 \pm 10)$ deg, $(115 \pm 10)$ deg, and
$(150 \pm 10)$ deg. Our results suggest the existence of an ordered magnetic
field aligned with the Magellanic Bridge direction and SMC's Bar in the NE
region, which have position angles roughly at $115.4$ deg and $45$ deg,
respectively. However, the overall magnetic field structure is fairly complex.
The trends at $115$ deg and $150$ deg may be correlated with the SMC's bimodal
structure, observed in Cepheids' distances and HI velocities. We derived a
value of $B_{sky} = (0.947 \pm 0.079)~\mu G$ for the ordered sky-projected
magnetic field, and $\delta B = (1.465 \pm 0.069)~\mu G$ for the turbulent
magnetic field. This estimate of $B_{sky}$ is significantly larger (by a factor
of $\sim10$) than the line-of-sight field derived from Faraday rotation
observations, suggesting that most of the ordered field component is on the
plane of the sky. A turbulent magnetic field stronger than the ordered field
agrees with observed estimates for other irregular and spiral galaxies. For the
SMC the $B_{sky}/\delta B$ ratio is closer to what is observed for our Galaxy
than other irregular dwarf galaxies.
