A possible bright ultraviolet flash from a galaxy at redshift z ~ 11

TL;DR

This paper reports a near-infrared transient at z ~ 11, potentially linked to a long gamma-ray burst, indicating such energetic events could occur as early as 420 million years after the Big Bang.

Contribution

It presents the first possible detection of a UV flash from a galaxy at z ~ 11, suggesting early universe gamma-ray bursts are observable.

Findings

Transient consistent with a long GRB UV flash

Detected at z ~ 11, earliest such event observed

Supports the existence of energetic explosions 420 million years after Big Bang

Abstract

In the optical sky, minutes-duration transients from cosmological distances are rare. Known objects that give rise to such transients include gamma-ray bursts (GRBs), the most luminous explosions in the universe that have been detected at redshift as high as z ~ 9.4. These high-redshift GRBs and their associated emission can be used to probe the star formation and reionization history in the era of cosmic dawn. Here we report a near-infrared transient with an observed duration shorter than 245 s coincident with the luminous star-forming galaxy GN-z11 at z ~ 11. The telluric absorption shown in the near-infrared spectrum indicates its origin from above the atmosphere. We can rule out the possibility of known man-made objects or moving objects in the Solar system based on the observational information and our current understanding of the properties of these objects. Since some long-duration GRBs are associated with a bright ultraviolet (UV) or optical flash, we investigate the possibility that the detected signal arose from a rest-frame UV flash associated with a long GRB from GN-z11. Despite the very low probability of being a GRB, we find that the spectrum, brightness, and duration of the transient are consistent with such an interpretation. Our result may suggest that long GRBs can be produced as early as 420 million years after the Big Bang.