Letter to the Editor

Lyman continuum escaping from in situ formed stars in a tidal bridge at z = 3

¹ The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova 10691 Stockholm, Sweden
² Minnesota Institute for Astrophysics, University of Minnesota 116 Church Street SE Minneapolis MN 55455, USA
³ Institute for Astronomy, University of Edinburgh, Royal Observatory Edinburgh EH9 3HJ, UK
⁴ International Space Science Institute Hallerstrasse 6 3012 Bern, Switzerland
⁵ Department of Astronomy, University of Michigan 1085 S. University Ave Ann Arbor MI 48109, USA
⁶ IPAC, California Institute of Technology 1200 E. California Blvd. Pasadena CA 91125, USA
⁷ Department of Astronomy, University of California, Berkeley Berkeley CA 94720, USA
⁸ Department of Astronomy and Astrophysics, University of Chicago 5640 South Ellis Avenue Chicago IL 60637, USA
⁹ Kavli Institute for Cosmological Physics, University of Chicago Chicago IL 60637, USA
¹⁰ Institute of Theoretical Astrophysics, University of Oslo P.O. Box 1029 Blindern NO-0315 Oslo, Norway
¹¹ Astrophysics Science Division, Code 660, NASA Goddard Space Flight Center 8800 Greenbelt Rd. Greenbelt MD 20771, USA

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 23 December 2025
Accepted: 5 February 2026

Abstract

We present an analysis of archival JWST NIRSpec IFS and HST imaging observations of the z = 3 Lyman continuum emitter (LCE) candidate LACES104037. We show that a nearby galaxy, denoted LACES104037-S, has a redshift offset from the main galaxy by only ∼ 450 km s⁻¹. Together with the identification of a tidal bridge between the galaxies, this indicates that the galaxies are interacting and most likely in the early stages of a merger. We show that the rest-frame LCE cluster sits ∼ 2.7 kpc from the galaxy core in the tidal bridge. It is faint in the nonionizing stellar continuum and shows faint but nonnegligible Hα and [O III] emission, suggesting that much of the gas surrounding the LCE cluster has been dispersed by feedback in the shallower gravitational potential of the tidal bridge. Comparing the direct LyC escape and the local Hα emission, we find a total ionizing escape fraction of f_esc^LyC =57 ± 8% from the LCE cluster. We estimate the age of the LCE cluster to ≲ 6.5 Myr, indicating that the cluster must have formed in situ in the tidal bridge well after the time of closest interaction. LyC escape from tidal stripping or in situ formed stars in tidal features would depend less on intrinsic galaxy properties than typically observed in low-z LCE surveys and could help explain the higher cosmic escape fraction and enhanced diversity of LCE galaxy properties observed at cosmic noon.