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The first generation of galaxies is expected to form in minihalos, accretinggas through ${\rm H}_2$ cooling, and possessing unique properties. Althoughunlikely to be directly detected in UV/infrared surveys, the radiation fromthese molecular-cooling galaxies (MCGs) could leave an imprint in the 21-cmsignal from the Cosmic Dawn. Here we quantify their detectability with upcomingradio interferometers. We generate mock 21-cm power spectra using a model forboth MCGs as well as more massive, atomic-cooling galaxies (AGCs), allowingboth populations to have different properties and scaling relations. The galaxyparameters are chosen so as to be consistent with: (i) high-redshift UVluminosity functions; (ii) the upper limit on the neutral fraction from QSOspectra; (iii) the Thomson scattering optical depth to the CMB; and (iv) thetiming of the recent putative EDGES detection. The latter implies a significantcontribution of MCGs to the Cosmic Dawn, if confirmed to be cosmological. Wethen perform Bayesian inference on two models including and ignoring MCGcontributions. Comparing their Bayesian evidences, we find a strong preferencefor the model including MCGs, despite the fact that it has more freeparameters. This suggests that if MCGs indeed play a significant role in theCosmic Dawn, it should be possible to infer their properties from upcoming21-cm power spectra. Our study illustrates how these observations candiscriminate among uncertain galaxy formation models with varying complexities,by maximizing the Bayesian evidence.

A tale of two sites -- II: Inferring the properties of minihalo-hosted galaxies with upcoming 21-cm interferometers