Probing the very high redshift Universe with Gamma-ray Bursts: prospects for observations with future X-ray instruments

TL;DR

This paper explores how future X-ray telescopes can enhance the study of high-redshift Gamma-Ray Bursts, aiding in understanding the early universe, cosmic re-ionization, and Population III stars.

Contribution

It proposes the use of next-generation X-ray instruments to complement infrared observations for studying the early universe through GRBs.

Findings

X-ray data can provide accurate redshift measurements for bright GRBs.

X-ray observations can help study metallicity in high-redshift GRBs.

Potential signatures of Population III star GRBs in X-ray band are discussed.

Abstract

Gamma-Ray Bursts (GRBs) are the most violent explosions in the Universe. Long duration GRBs are associated with the collapse of massive stars, rivaling their host galaxies in luminosity. The discovery of the most distant spectroscopically confirmed object in the Universe, GRB090423, opened a new window on the high redshift Universe, making it possible to study the cosmic 're-ionization' epoch and the preceding dark ages, as well as the generation of the first stars (Population III) using GRBs. Obviously this enables a wealth of new studies using the near infrared (nIR) characteristics of GRB afterglows. Here we explore a different path, focusing on the next generation of X-ray missions with large area focusing telescopes and fast repointing capabilities. We found that X-ray data can complement nIR observations and for the brightest GRBs can provide an accurate and independent redshift determination. Metallicity studies can also be carried out profitably once the redshift is known. Finally we discuss observational signatures of GRBs arising from Population III stars in the X-ray band.