We analyze the spectral asymmetry of Stokes V (circularly polarized) profiles
of an individual network patch in the quiet Sun observed by Sunrise/IMaX. At a
spatial resolution of 0.15"-0.18", the network elements contain substructure
which is revealed by the spatial distribution of Stokes V asymmetries. The area
asymmetry between the red and blue lobes of Stokes V increases from nearly zero
at the core of the structure to values close to unity at its edges (one-lobed
profiles). Such a distribution of the area asymmetry is consistent with
magnetic fields expanding with height, i.e., an expanding magnetic canopy
(which is required to fulfill pressure balance and flux conservation in the
solar atmosphere). Inversion of the Stokes I and V profiles of the patch
confirms this picture, revealing a decreasing field strength and increasing
height of the canopy base from the core to the periphery of the network patch.
However, the non-roundish shape of the structure and the presence of negative
area and amplitude asymmetries reveal that the scenario is more complex than a
canonical flux tube expanding with height surrounded by downflows.Comment: accepted for publication in ApJ Letter
