Galaxies colliding in early universe leak intense radiation at record rates
Astronomers using the James Webb Space Telescope observed two colliding galaxies 11 billion years ago that shed over half their ionizing radiation into space—the highest escape rate yet measured at that cosmic epoch. The finding reshapes understanding of how galaxy mergers trigger radiation release, with implications for modeling early universe reionization and refining predictions for next-generation space telescope surveys.
Originaltitel: Lyman continuum escaping from in situ formed stars in a tidal bridge at <i>z</i> = 3
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 H α 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 H α 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.