To recognize or reconstruct the magnetic field structure from the simulated RM map and assess their reliability.įaraday rotation model for different magnetic fields Recognition of a magnetic field model by fitting RMreg and RMmodel StepsTo simulate the RM maps of a typical spiral galaxy for - the regular and turbulent magnetic field models (disk and halo) - the thermal electron density modelĢ. The aim is to estimate the required number density of polarized sources to be detected with the SKA for reliable recognition or reconstruction of the magnetic field structure in nearby spiral galaxies. T.G.Arshakian, R.Beck and M.Krause (MPIfR, Bonn) R.Stepanov and P.Frick (ICMM, Perm) submitted to A&ATesting the magnetic field models of spiral galaxies with the SKASKADS science simulations
Galactic 3D models: disk emission well modeled, in agreement with all observationsstrong toroidal halo magnetic field needed Faraday depolarization effects not fully understoodHigh resolution simulations for the SKA:possible for a patch of sky (limited by available memory) Strong depolarization at 1.4 GHz large RM fluctuations along the line of sight by a small Ne filling factor and a coupling of the random field with Ne Synchrotron emission longitude disk CR electron component and 3 G random field profiles: 408 MHz I/22.8 GHz PI component Observational features versus model constrainsHigh-latitude RM asymmetry antisymmetric toroidal halo field, regular field strength (to the plane and center) up to 10 G, CR up to 1 kpc Galactic 3D emission model includes the distribution of B (disk and halo)nCR (disk: 2 kpc) ne (thick and thin disks and arms Cordes & Lazio 2002)ĭisk fields: ASS (Axisymmetric Spiral) + reversals in arms Fit of RMs in the plane Fits of 408MHz I Simulation code: HAMMURABI (Waelkens 2005) HealPix pixelization for each pixel I/U/Q/RM were calculated by integration along the LOS Final result: frequency-dependent all-sky maps (20 MHz to 22 GHz) Observations used to constrain the model:All-sky intensity maps (4 MHz 22.8 GHz - WMAP)All-sky polarization maps (1.4 GHz 22.8 GHz)Rotation measures of extragalactic sources (~1800 NVSS sources Han et al. Enlin (MPE Garching) submitted to AA Aim is to develop a Galactic 3D-model which will produce all-sky maps in total intensity, linear polarization and rotation measure SKADS in the MPI fr Radioastronmie (Bonn)the Galaxy and nearby spiral galaxies M 51 VLA+Eff 6cm (Fletcher & Beck) Understand the origin and evolution of magnetism in the Galaxy, extragalactic objects, clusters and inter-galactic/-cluster space.