Determine whether existing cold-source catalogues already exclude complete cold shells

Determine whether existing far-infrared and submillimetre catalogues contain objects whose properties exclude complete cold Slysh shells, after applying source classification and technosignature discriminants.

Background

The paper predicts that complete cold shells with temperatures of approximately 5–20 K would be exceptionally bright and could be detected over kiloparsec-scale distances in Planck-like submillimetre surveys. Such shells may therefore already be present in existing compact-source catalogues if they exist in the surveyed volume.

The unresolved issue is not raw sensitivity but whether catalogue sources can be reliably classified using stellar associations, morphology, spectral greyness, environmental context, line emission, and astrometric information. A dedicated analysis is needed to determine whether current catalogues already constrain or rule out this population.

References

Whether existing catalogued cold sources already exclude this possibility is uncertain in our view - classification rather than raw sensitivity is the limiting issue.

— Slysh haloes: the waste heat of cold computing as a submillimetre technosignature  (2608.31153 - Garrett, 31 Aug 2026) in Section 6.2, “The complete-shell limiting case”