Forward modeling of a pseudostreamer

We use the flux-rope insertion method to construct nonlinear force-free field (NLFFF) models constrained by observed Solar Dynamics Observatory (SDO)/AIA coronal structures and the SDO/Helioseismic Magnetic Imager photospheric magnetogram. The resulting magnetic field models are forward-modeled to produce synthetic data directly comparable to Mauna Loa Solar Observatory/Coronal Multichannel Polarimeter (CoMP) observations of the intensity and linear polarization of the Fe XIII 1074.7 nm infrared coronal emission line using FORWARD.

In addition, we determine the location of quasi-separatrix layers in the magnetic models, producing a Q-map from which the signatures of magnetic null points and separatrices can be identified. An apparent magnetic null observed in linear polarization by CoMP is reproduced by the model and appears in the region of the 2D-projected magnetic null in the Q-map. Further, we find that the height of the CoMP null is better reproduced by our NLFFF model than by the synthetic data we produce with potential-field source-surface models, implying the presence of a flux rope in the northern lobe of the pseudostreamer.