Analysis of magnetic fields in a plage region using a spatially coupled 2D inversion technique

The properties of magnetic features (MFCs) within a plage region in the vicinity of a sunspot were investigated at high spatial resolution. Stokes spectra of the 630nm line pair recorded by the spectropolarimeter aboard Hinode were inverted using an extended version of the SPINOR code. The code preformed a spatially coupled inversion of the Stokes spectra using three log(tau) nodes in optical depth. No magnetic filling factors was employed. The analysis of the inversion results reveals that the MFCs have typical field strengths of 1500G at log(tau)=-0.9 and inclinations between 10-15 degrees in all three log(tau) nodes. The MFCs expand by forming magnetic canopies composed of weaker and more inclined magnetic fields. The expansion of the magnetic field and temperature stratification of MFCs with optical depth is in good agreement with a thin flux tube model. Whilst the gas inside magnetic flux concentrations is typically at rest, the majority of MFCs were surrounded by a ring of downflows with an average value of 2.5km/s at log(tau)=0. The ring gradually shifts outwards following the expansion of the MFC. Within the downflow rings of MFCs small magnetic patches of opposite polarity to that of the main MFC were identified, which are predominantly situated beneath the canopy of its main MFC. We found evidence for a strong broadening of the Stokes profiles within MFCs and their surrounding downflow rings (expressed by a microturbulence in the inversion). This indicates the presence of strong unresolved velocities.

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