Tracing the feedback of high-z AGNs with LOFAR

High-redshift (z>4) quasars are essential in studying the growth of supermassive black holes and the evolution of active galactic nuclei (AGN) in the early Universe. The mere existence of black holes with a few million solar masses or more at high redshifts provide constraints on the black hole growth and accretion process. The radio-loud subsample of these sources is of great importance since they can be studied with the highest angular resolution provided by radio interferometric technique. Among them, high-redshift radio galaxies are important ingredients to study the evolution of large-scale structure in the Universe and feedback process since they are often found in the centre of clusters and proto-clusters.