Gamma-ray bursts as tracers of star-formation rate and metallicity evolution with THESEUS

TL;DR

Gamma-ray bursts serve as powerful tools to trace star formation and galaxy evolution in the early universe, and the THESEUS mission will significantly increase high-redshift GRB detections, advancing our understanding of cosmic chemical enrichment.

Contribution

This paper highlights how the THESEUS mission will enhance the detection of high-redshift GRBs, enabling detailed studies of early universe star formation and galaxy evolution.

Findings

Expected detection of over 100 GRBs at z>5 by THESEUS

GRBs provide unique insights into gas properties of host galaxies

Enhanced understanding of cosmic chemical enrichment

Abstract

The class of long gamma-ray bursts (LGRBs) is associated with the collapse of the most massive stars, making them a tool to investigate star formation in the early Universe. Furthermore, thanks to their exceptional brightness, LGRB afterglows can be used as extra-galactic background sources capable of unveiling the properties of the cold/warm gas of their hosting galaxies, up to the highest redshifts. Therefore LGRBs allow, uniquely, the combination of the information on different phases of the gas, through the absorption lines present in the afterglow spectra and the emission (continuum and lines) properties obtained from host galaxy photometry and spectroscopy, once the afterglow disappeared. To date, the main problem to carry out this kind of studies at very high redshift is the poor number of GRBs detected at $z>5$. The THESEUS mission will hugely increase such number, as it is expected to detect $>100$ GRBs at $z>5$. Therefore, THESEUS will bring a unique and fundamental contribution to the understanding of the chemical enrichment of the universe and of the evolution of galaxies and star formation up to the highest redshift.