Oral Presentation

Anisotropic Structure of Synchrotron Polarization

Author(s): Hyeseung Lee (KASI), Jungyeon Cho (Chungnam National University), Alex Lazarian (University of Wisconsin-Madison)

Presenter: Hyeseung Lee (Korea Astronomy and Space Science Institute (KASI))

Polarized synchrotron intensity arising from magnetized turbulence are anisotropic along the direction of mean magnetic field. Polarized synchrotron emission can be used to trace the direction of the mean magnetic field. I will introduce statistical description of anisotropy of polarized synchrotron intensity. In our work, we used second-order structure function and a new statistics, quadrupole moment, at different wavelengths. Second-order structure function visualizes anisotropy of polarized intensity along the direction of mean magnetic field. Using quadrupole moment, we quantify the degree of anisotropy displayed in the structure function. Since Faraday rotation, which depends on wavelength, can change the structure of polarized intensity and result in depolarization, we studied how the anisotropic structure changes with wavelength. First, we considered polarized synchrotron emission arising from one spatial region, in which synchrotron emission and Faraday rotation occur simultaneously. Second, we also considered polarized synchrotron emission from two spatially separated regions. When the wavelength is very small, the observed polarization exhibits the averaged structures of both foreground and background regions. As a wavelength increases and Faraday rotation becomes important, depolarization wipes out large scale structures, while small scale anisotropy begins to reflect that of the foreground region, where depolarization effect has relatively weak influence.