Near-infrared imaging polarimetry and modelling of NGC 4151

We present subarcsec resolution imaging polarimetry of the Seyfert 1 galaxy NGC 4151 in the J (1.23 mum) and H (1.64 mum) bands. The polarized flux images show elongated emission in both near-infrared bands, mainly to the north-east along a position angle of 30degrees. Detailed modelling indicates that the observed polarization can be reproduced by scattering in a very broad bi-conical structure, and in the region of the disc of the host galaxy illuminated by the AGN. The forward scattering and illumination cone has a half-opening angle of 60degrees and is at an inclination of 40degrees to the line of sight. To produce the best fit to the observations, an optically thick torus is required to attenuate the view to the bulk of the counter-scattering cone in the north-eastern direction. This torus has an outer radius of approximate to15 pc, consistent with the constraints from radio observations.