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Kardashev Type III civilisations have by definition energy requirements thatare likely to generate strong excess emission in the mid-infrared (MIR) that isassociated with the waste heat they generate. For those civilisations thatcapture starlight via Dyson sphere like constructions, the Optical to MIR fluxratio of the host galaxies is also expected to be unusually low. Since a widerange of galaxy types adhere to the infrared-radio correlation (IRC), galaxieshosting Type III civilisations should also strongly deviate from this relation.Radio data can therefore play a crucial role in breaking the degeneracy betweenthe effects of dust obscuration in a galaxy and the signature of anenergy-intensive civilisation. We have used the newly released LoTSS-DR1value-added catalogue to create a sample of 16,367 $z < 0.2$ sources with radioand MIR flux densities, optical photometry and (photometric) redshifts. Wecalculated the IRC parameter $q^{{\rm22~\mu m}}_{{\rm 150~MHz}}$ =log($S_{150~{\rm MHz}}$/$S_{22~{\rm \mu m}}$) and identified 21 sources withexceptionally high values of $q^{{\rm22~\mu m}}_{{\rm 150~MHz}}$, an indicationof MIR emission enhanced by a factor of $\sim$ 10. Out of the 21 high $q$-valuesources, 4 sources have very red MIR colors, and appear to have relatively lowoptical/MIR ratios. Two of the 4 sources are not well known in the literature,they are considered as potential hosts of Type III civilisations. These sourcesdeserve further study and investigation. Finally, we note that extending ouranalysis to the full LoTSS survey area can place very strong constraints on theincidence of Type III civilisations in the universe.

Searching for Kardashev Type III civilisations from High $q$-Value Sources in the LoTSS-DR1 Value-added Catalogue