Explain the S3 edge trends through contamination and detector-response modeling

Explain the behavior of the E0102 Ne X Ly-alpha line normalizations at low and high chipy on the ACIS-S3 CCD by determining the respective contributions of the contamination-layer spatial model, charge-transfer inefficiency, gain effects, and modifications to the detector response files.

Background

The E0102 Ne X Ly-alpha measurements at low and high chipy on the ACIS-S3 CCD exhibit scatter and temporal behavior that cannot be explained satisfactorily by the current spatial contamination model alone. The authors identify detector effects, particularly charge-transfer inefficiency and gain calibration, as possible contributors.

The unresolved issue is how to combine revisions to the contamination model with revisions to the detector response files so that the observed low- and high-chipy behavior is fully accounted for.

References

Finally, the behavior of the E0102 \ion{Ne}{x}~Ly$\alpha$ line normalizations at low and high chipy on S3 are difficult to explain in terms of the spatial model of the contamination alone. It is likely that detector effects such as CTI and gain are contributing to the scatter in these measurements and a combination of modifications to the contamination model and detector response files will be needed to fully explain these results.

— The Evolution of the ACIS Contamination Layer on the Chandra X-ray Observatory from 2010 to 2026  (2608.14363 - Plucinsky et al., 14 Aug 2026) in Section 5, Conclusions