OPTICAL AND NEAR-INFRARED POLARIMETRY OF HIGHLY REDDENED Type Ia SUPERNOVA 2014J: PECULIAR PROPERTIES OF DUST IN M82

We present optical and near-infrared multi-band linear polarimetryof the highly reddened Type Ia supernova (SN) 2014J that appeared in M82. SN 2014J exhibits large polarizationat shorter wavelengths, e.g., 4.8% in the B band, which decreases rapidly at longer wavelengths, while the position angleof the polarizationremains at approximately 40° over the observed wavelengthrange. These polarimetric properties suggest that the observed polarizationis likely predominantly caused by the interstellar dust within M82. Further analysis shows that the polarizationpeaks at a wavelengthsmuch shorter than those obtained for the Galactic dust. The wavelengthdependence of the polarizationcan be better described by an inverse power law rather than by the Serkowski law for Galactic interstellar polarization. These points suggest that the nature of the dust in M82 may be different from that in our Galaxy, with polarizingdust grains having a mean radius of <0.1 μm.