Effects of Depolarizing Intervening Galaxies on Background Radio Emission
speaker: Rikuto Omae
Abstract:
External galaxies often intervene in front of background radio sources such as quasars and radio galaxies. Such intervening galaxies affect observed polarization properties of the sources due to magnetic fields in the galaxies. Exploring the depolarizing intervening galaxies (DINGs) is thus a powerful tool to investigate the cosmological evolution of galactic magnetic field. In this talk, we focus on the global disk magnetic field, a primary component of galactic magnetic fields, and investigate the effects of DINGs on background radio emission using a simple model. We find that the degree of depolarization significantly depends on the inclination angle of the DING. When the DING is close to the edge-on view, depending on the angular size of background source relative to the DING, the Faraday dispersion function exhibits two components due mainly to the filling factor of the DING. Monte Carlo simulations suggest that DING’s contribution to the observed RM depends on the DING’s redshift.