An X-ray Detection of Star Formation In a Highly Magnified Giant Arc

TL;DR

This paper reports the first X-ray detection of star formation in a highly magnified, strongly lensed galaxy from the early universe, providing new insights into high-energy phenomena and re-ionization processes.

Contribution

It presents the first X-ray observation of a strongly lensed, high-redshift star-forming galaxy, opening new avenues for studying early galaxy formation.

Findings

Detected X-ray emission from a distant, lensed galaxy.

The galaxy is a low-mass, low-metallicity starburst with elevated X-ray emission.

X-ray emission may influence re-ionization in the early universe.

Abstract

In the past decade, our understanding of how stars and galaxies formed during the first 5 billion years after the Big Bang has been revolutionized by observations that leverage gravitational lensing by intervening masses, which act as natural cosmic telescopes to magnify background sources. Previous studies have harnessed this effect to probe the distant universe at ultraviolet, optical, infrared and millimeter wavelengths. However, strong lensing studies of young, star-forming galaxies have never extended into X-ray wavelengths, which uniquely trace high-energy phenomena. Here we report an X-ray detection of star formation in a highly magnified, strongly lensed galaxy. This lensed galaxy, seen during the first third of the history of the Universe, is a low--mass, low--metallicity starburst with elevated X-ray emission, and is a likely analog to the first generation of galaxies. Our measurements yield insight into the role that X-ray emission from stellar populations in the first generation of galaxies may play in re-ionizing the Universe. This observation paves the way for future strong lensing-assisted X-ray studies of distant galaxies reaching orders of magnitude below the detection limits of current deep fields, and previews the depths that will be attainable with future X-ray observatories.