Abstract:

The huge luminosity, the redshift distribution extending up to z > 9 and the association with the explosive death of very massive stars make long Gamma-Ray Bursts (GRB) extremely powerful probes for the exploration of the Cosmic Dawn. Indeed, the NIR afterglow emission of GRBs allows the direct detection of exploding stars up to very high redshift and, at the same time, acts as a uniquely powerful cosmic beacon which enables the identification, accurate localization, redshift measurement and absorption spectroscopy of primordial galaxies independently on their mass and luminosity. Thus, very high-z GRBs are a unique tool for directly detecting first population of stars, unveiling and characterizing  the bulk population of low mass / luminosity primordial galaxies and exploring the evolution and sources of cosmic re-ionization. At the same time, the correlation between radiated energy and spectral photon peak energy ("Amati relation" enables the use of GRBs for measuring cosmological parameters, investigating the nature and evolution of "dark energy" and testing non-standard cosmological models. Finally, short GRBs, produced by the merging of NS-NS and NS-BH systems, sources of Gravitational Wave signals, are a key phenomenon for enabling Multi-messenger cosmology. Space mission concepts like THESEUS, under study by ESA, aim at fully exploiting these breakthrough potentialities of the GRB phenomenon for cosmology, also in synergy with the large e.m. (e.g., JWST. ELT, TMT, SKA, CTA, NewATHENA) and multi-messenger (e.g., ET, CE, Km3NET) facilities of the future.
 

Short Bio:

Dr. Lorenzo Amati is a high-energy astrophysicist who famously discovered the "Amati relation," a correlation between the spectral peak photon energy and the total radiated energy of gamma-ray bursts, which has significant implications for understanding GRB physics and their potential use in cosmology. Since 2017, Dr. Amati is the Director of Research at the Osservatorio di Astrofisica e Scienza dello Spazio (OAS) of INAF in Bologna and since August 2024, he is the Director of INAF - OAS. Dr. Amati is the Mission Principal Investigator and Lead Scientist for the THESEUS mission, currently under study by the European Space Agency (ESA),  aimed at investigating the early Universe and revolutionizing multi-messenger time domain astrophysics through the study of GRBs and other transient phenomena.