Determine whether J0011+3443 is affected by gravitational milli-lensing

Determine whether J0011+3443 is gravitationally milli-lensed by a dark or unresolved compact foreground mass despite the observed asymmetry between radio components A and B.

Background

J0011+3443 has two compact radio components with an approximately constant flux-density ratio and similar compact recovered spectra, properties that could initially be compatible with two lensed images of one background source. However, the 23.6 GHz VLBA image resolves component A into substructure while component B remains unresolved or marginally resolved, which disfavors a simple lensing interpretation because lensing preserves surface brightness and should generally reproduce corresponding substructure in both images.

No independently identified lower-redshift luminous deflector is known along the line of sight. Nevertheless, the observations do not rule out milli-lensing by a dark or unresolved compact foreground object. Deeper optical and near-infrared imaging is proposed to constrain possible foreground galaxies and thereby clarify this interpretation.

References

This does not, however, exclude milli-lensing by a dark or unresolved compact foreground mass.

— J0011+3443: a GPS compact symmetric object, gravitational lens, or dual AGN?  (2608.19928 - Traianou et al., 20 Aug 2026) in Section Discussion, subsection “Gravitational lensing”