RAMPAZZO, RobertoRobertoRAMPAZZOD'ONOFRIO, MAUROMAUROD'ONOFRIOZAGGIA, SimoneSimoneZAGGIADjorgovski, Stanislav GeorgeStanislav GeorgeDjorgovskiElmegreen, Debra M.Debra M.ElmegreenPOGGIANTI, Bianca MariaBianca MariaPOGGIANTICalzetti, DanielaDanielaCalzettiCombes, FrançoiseFrançoiseCombesLongair, Malcolm S.Malcolm S.LongairBromm, VolkerVolkerBromm2020-07-232020-07-232016978-3-319-31004-6http://hdl.handle.net/20.500.12386/26590Some contributions in Chap. 1 have highlighted the impact of the discovery in the 1960s of a handful of radio galaxies and Quasars in the redshift range z ∼ 0.2-0.4. About 40 years later, at the end of the twentieth Century, the systematic exploration of galaxies reached z ∼ 1-3. The combination of HST deep imaging and the coming into operation of the 8-10 m class telescopes with their spectroscopic capabilities, move ahead the limits. At the same time, astronomers greatly improved their strategies to hunt high-redshift galaxies. Today, it is not infrequent the spectroscopic confirmation of galaxies at z ∼ 7-8, pushing the detection limits more or less to the end of the re-ionization era. The gauntlet to observe the so called "first galaxies", i.e. those assembling during the first billion years of the cosmic time, is throw down.STAMPAenBook part10.1007/978-3-319-31006-0_6000389190800008https://link.springer.com/chapter/10.1007%2F978-3-319-31006-0_62016ASSL..435..479RFIS/05 - ASTRONOMIA E ASTROFISICA