Thermal Diagnostics with the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory: A Validated Method for Differential Emission Measure Inversions

TL;DR

This paper introduces a validated, fast linear programming method for differential emission measure inversions using AIA solar images, enabling routine thermal mapping of the solar corona with improved accuracy when combined with XRT data.

Contribution

A new positive definite DEM inversion technique validated against diverse models and adaptable for combined AIA and XRT data, enhancing routine solar corona thermal diagnostics.

Findings

Method produces positive definite DEM solutions.

Validated against idealized and realistic models.

Improves thermal structure mapping when combined with XRT data.

Abstract

We present a new method for performing differential emission measure (DEM) inversions on narrow-band EUV images from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). The method yields positive definite DEM solutions by solving a linear program. This method has been validated against a diverse set of thermal models of varying complexity and realism. These include (1) idealized gaussian DEM distributions, (2) 3D models of NOAA Active Region 11158 comprising quasi-steady loop atmospheres in a non-linear force-free field, and (3) thermodynamic models from a fully-compressible, 3D MHD simulation of AR corona formation following magnetic flux emergence. We then present results from the application of the method to AIA observations of Active Region 11158, comparing the region's thermal structure on two successive solar rotations. Additionally, we show how the DEM inversion method can be adapted to simultaneously invert AIA and XRT data, and how supplementing AIA data with the latter improves the inversion result. The speed of the method allows for routine production of DEM maps, thus facilitating science studies that require tracking of the thermal structure of the solar corona in time and space.