Simulated Faraday Rotation Measures toward High Galactic Latitudes

Abstract

We study the Faraday rotation measure (RM) due to the Galactic magnetic field (GMF) toward high Galactic latitudes. The RM arises from the global, regular component as well as from the turbulent, random component of the GMF. We model the former based on observations and the latter using the data of magnetohydrodynamic turbulence simulations. For a large number of different GMF models, we produce mock RM maps around the Galactic poles and calculate various statistical quantities with the RM maps. We find that the observed medians of RMs toward the north and south Galactic poles, $\sim 0.0\pm 0.5\mathrm{rad}{\mathrm{m}}^{-2}$ and $\sim +6.3\pm 0.5\mathrm{rad}{\mathrm{m}}^{-2}$, are difficult to explain with any of our many alternate GMF models. The standard deviation of observed RMs, $\sim 9\mathrm{rad}{\mathrm{m}}^{-2}$, is clearly larger than that of simulated RMs. The second-order structure function of observed RMs is substantially larger than that of simulated RMs, especially at small angular scales. We discuss other possible contributions to RM toward high Galactic latitudes. Besides observational errors and the intrinsic RM of background radio sources against which RM is observed, we suggest that the RM due to the intergalactic magnetic field may account for a substantial fraction of the observed RM. Finally we note that reproducing the observed medians may require additional components or/and structures of the GMF that are not present in our models.

To appear in ApJ. Pdf with full resolution figures can be downloaded from http://canopus.cnu.ac.kr/ryu/arkg.pdf

References in corpus (10)

• Turbulence and Magnetic Fields in the Large Scale Structure of the Universe
• Radio observational constraints on Galactic 3D-emission models
• The Vertical Structure of Warm Ionised Gas in the Milky Way
• The outer scale of turbulence in the magneto-ionized Galactic interstellar medium
• A Global Probe of Cosmic Magnetic Fields to High Redshifts
• The Turbulent Warm Ionized Medium: Emission Measure Distribution and MHD Simulations
• Simulating polarized Galactic synchrotron emission at all frequencies, the Hammurabi code
• Dynamo activities driven by magneto-rotational instability and Parker instability in galactic gaseous disk
• Galactic Dynamos and Galactic Winds
• Global Three-Dimensional MHD Simulations of Galactic Gaseous Disks: I. Amplification of Mean Magnetic Fields in Axisymmetric Gravitational Potential

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