Probing the Origin of the Star Formation Excess Discovered by JWST through Gamma-Ray Bursts

TL;DR

This paper suggests gamma-ray bursts can be used to investigate the unexpected abundance of bright galaxies at high redshifts observed by JWST, helping to understand early universe star formation.

Contribution

It introduces the use of gamma-ray bursts as a probe to explore the origin of the star formation excess detected by JWST at high redshifts.

Findings

EP can detect several GRBs annually at z>10

GRB event rate may show an excess at z≈10 depending on scenarios

Follow-up observations could reveal dark GRBs in red, compact galaxies

Abstract

The recent observations by the James Webb Space Telescope (JWST) have revealed a larger number of bright galaxies at $z\gtrsim10$ than was expected. The origin of this excess is still under debate, although several possibilities have been presented. We propose that gamma-ray bursts (GRBs) are a powerful probe to explore the origin of the excess and, hence, the star and galaxy formation histories in the early universe. Focusing on the recently launched mission, Einstein Probe (EP), we find that EP can detect several GRBs annually at $z\gtrsim10$, assuming the GRB formation rate calibrated by events at $z\lesssim6$ can be extrapolated. Interestingly, depending on the excess scenarios, the GRB event rate may also show an excess at $z\simeq10$, and its detection will help to discriminate between the scenarios that are otherwise difficult to distinguish. Additionally, we discuss that the puzzling, red-color, compact galaxies discovered by JWST, the so-called ``little red dots'', could host dark GRBs if they are dust-obscured star forming galaxies. We are eager for unbiased follow-up of GRBs and encourage future missions such as HiZ-GUNDAM to explore the early universe.