The impact of limited time resolution on the forward-scattering polarization in the solar Sr I 4607 \AA\ line

TL;DR

This study examines how limited time resolution affects the detection of forward-scattering polarization signals in the Sr I 4607 Å line, using advanced 3D radiative transfer models and comparing with recent observations.

Contribution

It provides the first analysis of the impact of time resolution on forward-scattering polarization signals in the Sr I line using detailed 3D radiative transfer simulations.

Findings

Good agreement between theoretical polarization patterns and recent observations.

Limited time resolution can significantly affect the observability of polarization signals.

Predictions for future observations with the Daniel K. Inouye Solar Telescope.

Abstract

Theoretical investigations predicted that high spatio-temporal resolution observations in the Sr I 4607 A line must show a conspicuous scattering polarization pattern at the solar disk-center, which encodes information on the unresolved magnetism of the inter-granular photospheric plasma. Here we present a study of the impact of limited time resolution on the observability of such forward scattering (disk-center) polarization signals. Our investigation is based on three-dimensional radiative transfer calculations in a time-dependent magneto-convection model of the quiet solar photosphere, taking into account anisotropic radiation pumping and the Hanle effect. This type of radiative transfer simulation is computationally costly, reason why the time variation had not been investigated before for this spectral line. We compare our theoretical results with recent disk-center filter polarimetric observations in the Sr I 4607 A line, showing that there is good agreement in the polarization patterns. We also show what we can expect to observe with the Visible Spectro-Polarimeter at the upcoming Daniel K. Inouye Solar Telescope.