JWST reveals a supernova following a gamma-ray burst at z $\simeq$ 7.3

TL;DR

This paper reports JWST observations of a gamma-ray burst at redshift 7.3, revealing a supernova and host galaxy, providing insights into early universe star formation and GRB progenitors.

Contribution

First detection of a supernova associated with a high-redshift GRB at z~7.3 using JWST, linking early universe star properties to local GRB progenitors.

Findings

Detected supernova similar to SN 1998bw at z~7.3

Host galaxy is faint and blue, typical of early universe galaxies

Supernova brightness could be much higher than SN 1998bw

Abstract

The majority of energetic long-duration gamma-ray bursts (GRBs) are thought to arise from the collapse of massive stars, making them powerful tracers of star formation across cosmic time. Evidence for this origin comes from the presence of supernovae in the aftermath of the GRB event, whose properties in turn link back to those of the collapsing star. In principle, with GRBs we can study the properties of individual stars in the distant universe. Here, we present JWST/NIRCAM observations that detect both the host galaxy and likely supernova in the SVOM GRB 250314A with a spectroscopically measured redshift of z $\simeq$ 7.3, deep in the era of reionisation. The data are well described by a combination of faint blue host, similar to many z $\sim$ 7 galaxies, with a supernova of similar luminosity to the proto-type GRB supernova, SN 1998bw. Although larger galaxy contributions cannot be robustly excluded, given the evidence from the blue afterglow colours of low dust extinction, supernovae much brighter than SN 1998bw can be. These observations suggest that, despite disparate physical conditions, the star that created GRB 250314A was similar to GRB progenitors in the local universe.