The solar continuum intensity distribution: Settling the conflict between observations and simulations

TL;DR

This study resolves long-standing discrepancies between observed and simulated solar continuum intensity distributions by accounting for instrumental effects, demonstrating that modern simulations accurately reproduce the Sun's photospheric intensity contrast.

Contribution

It provides a detailed methodology for comparing observations and simulations by incorporating instrumental degradation effects, confirming the accuracy of current 3D radiative MHD models.

Findings

Observed intensity contrast is higher than ground-based estimates.

Simulations match observations when instrumental effects are considered.

Proper image degradation correction is essential for accurate comparison.

Abstract

For many years, there seemed to be significant differences between the continuum intensity distributions derived from observations and simulations of the solar photosphere. In order to settle the discussion on these apparent discrepancies, we present a detailed comparison between simulations and seeing-free observations that takes into account the crucial influence of instrumental image degradation. We use a set of images of quiet Sun granulation taken in the blue, green and red continuum bands of the Broadband Filter Imager of the Solar Optical Telescope (SOT) onboard Hinode. The images are deconvolved with Point Spread Functions (PSF) that account for non-ideal contributions due to instrumental stray-light and imperfections. In addition, synthetic intensity images are degraded with the corresponding PSFs. The results are compared with respect to spatial power spectra, intensity histograms, and the centre-to-limb variation of the intensity contrast. The observational findings are well matched with corresponding synthetic observables from three-dimensional radiation (magneto-)hydrodynamic simulations. We conclude that the intensity contrast of the solar continuum intensity is higher than usually derived from ground-based observations and is well reproduced by modern numerical simulations. Properly accounting for image degradation effects is of crucial importance for comparisons between observations and numerical models. It finally settles the traditionally perceived conflict between observations and simulations.