Forward modeling of emission in SDO/AIA passbands from dynamic 3D simulations

TL;DR

This study uses 3D radiative MHD simulations to analyze how different ions contribute to SDO/AIA passbands, revealing that some channels are significantly affected by non-dominant ions, impacting temperature diagnostics.

Contribution

It provides a detailed forward modeling approach to quantify the influence of non-dominant ions on AIA passbands under dynamic coronal conditions.

Findings

131, 171, and 304 Å channels are minimally affected by non-dominant ions.

Other channels show significant contributions from ions at different temperatures.

Element abundances and electron density influence the emission contributions.

Abstract

It is typically assumed that emission in the passbands of the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) is dominated by single or several strong lines from ions that under equilibrium conditions are formed in a narrow range of temperatures. However, most SDO/AIA channels also contain contributions from lines of ions that have formation temperatures that are significantly different from the "dominant" ion(s). We investigate the importance of these lines by forward modeling the emission in the SDO/AIA channels with 3D radiative MHD simulations of a model that spans the upper layer of the convection zone to the low corona. The model is highly dynamic. In addition, we pump a steadily increasing magnetic flux into the corona, in order to increase the coronal temperature through the dissipation of magnetic stresses. As a consequence, the model covers different ranges of coronal temperatures as time progresses. The model covers coronal temperatures that are representative of plasma conditions in coronal holes and quiet sun. The 131, 171, and 304 \AA{} AIA passbands are found to be least influenced by the so-called "non-dominant" ions, and the emission observed in these channels comes mostly from plasma at temperatures near the formation temperature of the dominant ion(s). On the other hand, the other channels are strongly influenced by the non-dominant ions, and therefore significant emission in these channels comes from plasma at temperatures that are different from the "canonical" values. We have also studied the influence of non-dominant ions on the AIA passbands when different element abundances are assumed (photospheric and coronal), and when the effects of the electron density on the contribution function are taken into account.