Observability of magnetic field in lensing galaxies using broadband radio polarization data
speaker: Omae Rikuto
Abstract:
External galaxies often intervene in front of background radio sources such as quasars and radio galaxies. Linear polarization of the background emission is depolarized by Faraday rotation of inhomogeneous magnetized plasma of the intervening galaxies. Exploring the depolarizing intervening galaxies can be a powerful tool to investigate the cosmological evolution of the galactic magnetic field. Recently, Mao et al. (2016) detected coherent μG magnetic fields in the lensing disk galaxy by exploiting the scenario where the polarized radio emission from a background source is gravitationally lensed by an intervening galaxy using broadband radio polarization data. The method is based on the difference in Faraday depths where the background source emission passes through different positions of the intervening galaxies due to the gravitational lensing effect. Using a galactic magnetic field model, we investigate how background polarized sources are observed due to gravitational lensing effects of intervening galaxies. We will discuss whether spectral changes and galactic magnetic fields can be estimated when RM structures are present in the region through which the background source emission passes.