The bulk of the quiet solar photosphere is thought to be significantly magnetized , due to the ubiquitous presence of a tangled magnetic field at subresolution scales with an average strength { \langle B \rangle } { \sim } 100 G. This conclusion was reached through detailed three-dimensional ( 3D ) radiative transfer modeling of the Hanle effect in the Sr i 4607 Å line , using the microturbulent field approximation and assuming that the shape of the probability density function of the magnetic field strength is exponential .
Here we relax both approximations by modeling the observed scattering polarization in terms of the Hanle effect produced by the magnetic field of a 3D photospheric model resulting from a ( state-of-the-art ) magneto-convection simulation with surface dynamo action .
We show that the scattering polarization amplitudes observed in the Sr i 4607 Å line can be explained only after enhancing the magnetic strength of the photospheric model by a sizable scaling factor , F { \approx } 10 , which implies { \langle B \rangle } { \approx } 130 G in the upper photosphere .
We argue also that in order to explain both the Hanle depolarization of the Sr i 4607 Å line and the Zeeman signals observed in Fe i lines we need to introduce a height-dependent scaling factor , such that the ensuing { \langle B \rangle } { \approx } 160 G in the low photosphere and { \langle B \rangle } { \approx } 130 G in the upper photosphere .