Abstract
Magnetic fields in the universe play an essential role in observations of the radio synchrotron continuum; however, we do not know enough about them, either observationally or theoretically. We are interested in galactic magnetic fields because they affect the structural formation of galaxies in terms of star-forming regions, spiral arms, and threads at the galactic center. To clarify the importance of magnetic fields, we carried out numerical simulations of the galactic gaseous disk with magnetic fields. We also calculated observables, such as the rotation measure and Stokes parameters, from the results of numerical simulation. FD maps and intensity maps have been reported, and the relation between azimuthal angle and FD has been shown to depend on the inclination of the observer. Furthermore, it has been shown that a polarized intensity below 800 MHz reflects field structure in the halo region, although the intensity is weak. The present paper summarizes the effects of Faraday depolarization and the relation between magnetic-field structure and Stokes parameters.
Highlights
Spiral galaxies have spiral arms in which the strength of magnetic fields is on the order of a microgauss μG
Because magnetic-field strength is defined by the plasma β, which is the ratio of gas pressure q to magnetic pressure, the unit strength of the magnetic field is proportional to the density B0 = ρ0 v20 = 26 μG
The line of sight (LOS) field direction is negative in the region around (5, −5), and yet part of the Faraday depth (FD) becomes positive
Summary
Spiral galaxies have spiral arms in which the strength of magnetic fields is on the order of a microgauss μG. Several numerical simulations have been performed to reveal the maintenance mechanism of the magnetic fields [3] These simulations produced a quasisteady state with a field strength of a few microgauss, similar to the observational results, though the mechanisms of amplification differed among the simulations. The topology of the magnetic field of a galaxy is classified by the relation between azimuthal angle and Faraday rotation measure (RM) (e.g., as an axisymmetric spiral (ASS) as seen in M31, or bisymmetric spiral (BSS) as possibly seen in M81). Faraday tomography recently revealed that the magnetic-field topology of M51 has the characteristics of both an ASS and BSS [4]. A mapping between the Faraday depth (FD) and spatial length is still needed to know the real distribution
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
