SALVATERRA, RubenRubenSALVATERRA2020-03-192020-03-1920152214-4048http://hdl.handle.net/20.500.12386/23396Acknowledgements This research was supported by the ASI-INAF contract ( 1/005/11/1 ). The author would like to thank A. Melandri for providing the X-ray light curve for the z > 6 sample, S. Campana for providing the measure of the N H , X for some of the high- z bursts, G. Ghirlanda for providing the E iso values and the expected rate of GRBs at z > 8 .Ten years of operations of the Swift satellite have allowed us to collect a small sample of long Gamma-Ray Bursts (GRBs) at redshift larger than 6. I will review here the present status of this research field and discuss the possible use of GRBs as a fundamental new tool to explore the early Universe, complementary to quasar and galaxy surveys. <P />STAMPAenArticle10.1016/j.jheap.2015.03.0012-s2.0-84941937751000213811200006https://www.sciencedirect.com/science/article/pii/S2214404815000051?via%3Dihub2015JHEAp...7...35SFIS/05 - ASTRONOMIA E ASTROFISICA