Signature of the interaction between dark sectors in the reionization process

We consider the reionization process in a cosmological model in which dark matter interacts with dark energy. Using a semi-analytical reionization model, we compute the evolution of the ionized fraction in terms of its spatial average and linear perturbations. We show that certain types of interactions between dark matter and dark energy can significantly affect the reionization history. We calculate the 21 cm signals in the interaction models, and compare the results with the predictions of the ${\rm \Lambda CDM}$ model.