A Magnified Compact Galaxy at Redshift 9.51 with Strong Nebular Emission Lines

TL;DR

This paper reports the discovery and spectroscopic analysis of a highly magnified galaxy at redshift 9.51, providing insights into early galaxy properties and nebular emission lines during the epoch of reionization.

Contribution

It presents the first JWST spectroscopic detection of a galaxy at z > 9 with strong nebular emission lines, revealing its compact size and high star formation rate.

Findings

Redshift of the galaxy is z = 9.51 ± 0.01.

Galaxy's radius is approximately 16 parsecs, more compact than similar luminosity galaxies at lower redshifts.

Detected strong nebular emission lines from oxygen and hydrogen.

Abstract

Ultraviolet light from early galaxies is thought to have ionized gas in the intergalactic medium. However, there are few observational constraints on this epoch because of the faintness of those galaxies and the redshift of their optical light into the infrared. We report the observation, in JWST imaging, of a distant galaxy that is magnified by gravitational lensing. JWST spectroscopy of the galaxy, at rest-frame optical wavelengths, detects strong nebular emission lines that are attributable to oxygen and hydrogen. The measured redshift is z = 9.51 +- 0.01, corresponding to 510 million years after the Big Bang. The galaxy has a radius of 16.2+4.6-7.2 parsecs, which is substantially more compact than galaxies with equivalent luminosity at z = 6 to 8, leading to a high star formation rate surface density.