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Supra-arcade downflows (SADs) are infrequent, wiggly opaque structuresobserved to descend through the solar corona, mostly in EUV and soft X-rayfrequencies. From their physical characteristics, SADs have been interpreted asvoided (subdense) bubbles and are related to magnetic reconnection processesduring long-term erupting flares. In this work we use numerical MHD simulationsto compute flux density maps, which are convolved with telescope beams tosynthesise images with the aim to assess the expected SADs emission at radiowavelengths and propose observing strategies, including the instruments thatcan be used. We assume that the emission is thermal bremsstrahlung from a fullyionised plasma without any appreciable gyroresonance contribution sincemagnetic fields are of the order of ~10 G. We find that SADs emission should beoptically thin in the frequency [10-1000] GHz range, and the spatiallyintegrated flux should be larger than 1 Jy. We conclude, therefore, thatobserving SADs in radio frequencies between [0.5-1000] GHz is feasible withpresent instrumentation. Moreover, since the emission is for the most partoptically thin, the flux density is proportional to temperature, density andline-of-sight depth, and when combined with EUV and soft X-ray images, mayallow a better density and temperature determination of SADs.

Estimating the coronal supra-arcade downflows radio emission: from centimetre through submillimetre wavelengths