Merging Signatures in an Offset Lyman Continuum Emitter at Redshift 3.8

TL;DR

This study investigates a high-redshift galaxy with offset Lyman continuum emission, revealing it as a merging system with enhanced star formation, and suggests mergers may facilitate ionizing photon escape during reionization.

Contribution

We present detailed analysis of an offset LyC emitter at z=3.8, demonstrating its nature as a merger with boosted star formation, highlighting mergers' potential role in LyC photon escape.

Findings

CDFS-6664 is a merging system with two components.

Offset LyC emission is linked to the bluer, younger component.

Mergers may enhance LyC photon escape in high-redshift galaxies.

Abstract

Lyman continuum (LyC) emitters at $z>3$ provide critical samples for studying the contribution of galaxies to the ionizing background in the Epoch of Reionization. We collect a sample of $z>3$ LyC emitters, a dominant fraction ($\sim$60%-70%) of which shows spatial offsets between LyC emission and the non-ionizing continuum. From this sample, especially, we find a case of an offset LyC emitter, CDFS-6664 ($z=3.797$), which shows two components in the high-resolution Hubble Space Telescope (HST) and James Webb Space Telescope (JWST) images. The exceptionally rich data set of CDFS-6664 enables us to extract the two components across multiple wavelengths and estimate their physical properties. We show that CDFS-6664 is consistent with a major merger system with boosted star formation in both components and the offset LyC emission is most likely associated with the bluer and younger component in this merging system. Our result offers an example in which the offset can be caused by a merger. Future observations of more offset LyC emitters would elucidate the role that mergers play in the escape of LyC photons.