Coalescence of Primordial Black Holes at High Redshifts with Clustering

The observation of gravitational waves from cosmological distances is one of the future tools for testing the hypothesis of the existence of primordial black holes (PBHs). Their clustering plays a decisive role in predicting their mergers. We show that in this case the merger rate differs from the predictions of the model without initial clustering. Also, our results on the merger rate are sensitive to the parameters of the PBH cluster formation models. Future observations of black hole mergers at high redshifts will be able to test the possibility of PBH clustering.