Near-infrared Polarimetric Survey of the Central Region of Our Galaxy

Shogo Nishiyama

We present results of near-infrared (NIR) polarimetric observations of the central region of our Galaxy. The observations have been carried out using the IRSF telescope in South Africa, and the Subaru telescope in Hawaii. The NIR polarization of point sources is useful to understand not only the nature of the point sources, but also the magnetic field configuration in the interstellar space. The NIR polarization of intrinsically unpolarized stars is attributed to differential extinction by dust grains aligned with their short axis along the direction of the magnetic field. And if we know the distance to the point sources, it is possible to obtain the magnetic field configuration projected onto the plane of the sky at a certain distance. Mainly we show the results of the NIR polarimetric survey of the central 3 degree by 2 degree region of our Galaxy. Using stars distributed at the far and near side of the Galactic center, we have derived a large scale map of the magnetic field at the central region of our Galaxy. This technique is applicable to the data sets of optical polarization. Optical large-field polarimetric surveys such as SGMAP will enable us to understand large-scale magnetic fields projected onto the sky, and change of them along the line of sight.