Whether JWST background subtraction removes a dark-matter decay signal

Determine whether the JWST data-reduction background-subtraction steps bkg_subtract and master_background can remove a spatially homogeneous spectral signal produced by decaying dark matter in the Milky Way halo.

Background

The search targets a diffuse dark-matter decay signal that would appear spatially homogeneous across the JWST field of view. The standard JWST background-subtraction procedures are designed to remove spatially smooth emission, creating a potential risk that they could also remove a genuine dark-matter line.

The authors disable these procedures in their fiducial reduction as a precaution and show that doing so does not materially change the derived sensitivities. However, they explicitly state that the possible removal of a real signal has not been demonstrated or ruled out; it remains a conjectured instrumental effect.