Horizontal or vertical magnetic fields on the quiet Sun: Angular distributions and their height variations

摘要

Different analyses of identical Hinode SOT/SP data of quiet-sun magneticfields have in the past led to contradictory answers to the question of whetherthe angular distribution of field vectors is preferentially horizontal orvertical. These answers have been obtained by combining the measured circularand linear polarizations in different ways to derive the field inclinations. Aproblem with these combinations is that the circular and linear polarizationsscale with field strength in profoundly different ways. Here, we avoid theseproblems by using an entirely different approach that is based exclusively onthe fundamental symmetry properties of the transverse Zeeman effect forobservations away from the disk center without any dependence on the circularpolarization. Systematic errors are suppressed by the application of a doublydifferential technique with the 5247-5250 \AA\ line pair for observations withthe ZIMPOL-2 imaging polarimeter on the French THEMIS telescope on Tenerife.This allows us to determine in a model- and resolution-independent way how theangular distribution of the intranetwork magnetic fields changes from beingpreferentially vertical in the lower and middle photosphere to becomepreferentially horizontal in the upper photosphere.