New insights into the study of magnetic field in the clumpy torus of AGN using near-infrared polarimetry

Abstract

We present J, H and K., imaging polarimetry of IC5063. N1R polarimetry observations may advance our understanding of the mechanisms of polarisation and hence magnetic field strength in the torus of AGN. In these proceedings we summarize the polarisation results of the central 1.2> aperture (̃263 pc) of IC5063. We present a simple polarising model to account for various mechanisms of polarisation in the central regions of IC5063. The model is consistent with dichroic absorption from diffuse stellar emission through dust in the nuclear bulge and electron scattering as dominant mechanisms of polarisation at J and H. Dichroic absorption from aligned dust grains within the torus of IC5063 is dominant at Kn with a visual extinction of A v = 48±2 mag by the torus. Through the use of various components to the central engine of IC5063, we estimated the intrinsic polarisation from dichroic absorption to be Pdic kn = 12.5 ± 2.7%. The dust grain alignment mechanism is assumed to be produced by paramagnetic relaxation. In this case, the intrinsic polarisation, P dic kn, and the visual extinction by the torus, A v, are related with the magnetic field strength. The magnetic field strength is estimated to be in the range of 12-128 mG, for the physical conditions and environments of the gas and dust in the NIR emitting regions of the torus of IC5063. © The Society of Geomagnetism and Earth Planetary and Space Sciences (SGEPSS).