Program: GS-2016A-DD-1

GRBs provide a unique window on exotic, highly relativistic physics. Our Gemini campaign on GRB090423 (z=8.2) and GRB 090429B (z_phot=9.4) demonstrates how GRBs can probe the epoch of re-ionization, pinpointing the earliest stars and galaxies. Furthermore, the Gemini-discovered GRB130603B afterglow demonstrated how short GRBs can aid our understanding of compact object binary systems and the production of r-process elements during their final stages. Our submitted proposal for the 2016A semester was not awarded time, but has been very highly ranked. Therefore, we feel compelled to submit the following DDT proposal, with a much more moderate time request, with a very narrow focus: (i) to observe GRBs at very high-z, in order to explore the ISM and IGM during reionization and place fundamental constraints on the early epochs of star-formation, (ii) to study in detail the class of short-duration gamma-ray bursts, especially their electromagnetic signatures in relation to gravitational-wave sources. The uncertain lifetime of the Swift satellite and the advent of Gravitational Wave experiments strongly motivate such observations, in particular from versatile facilities like the Gemini observatories.