High redshift massive protogalaxies, the sites of early star formation in the Universe, provided a suitable environment for the formation of the first supermassive black holes. Mass accretion causes the black hole to grow and become a gamma-ray blazar for those observers privileged by a line of sight parralel to the jet. Possible evolutionary sequences are explored in terms of their visibility in the millimeter, optical and gamma-ray regimes.

Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 3 (OG part 2), pages 1093-1096