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arXiv · 2505.01499

An extremely metal-poor Lyman $α$ emitter candidate at $z=6$ revealed through absorption spectroscopy

Dominika Ďurovčíková·Anna-Christina Eilers·Robert A. Simcoe·Louise Welsh·Romain A. Meyer·Jorryt Matthee·Emma V. Ryan-Weber·Minghao Yue·Harley Katz·Sindhu Satyavolu·George Becker·Frederick B. Davies·Emanuele Paolo Farina
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Abstract

We report the discovery of a Lyman $α$ emitter (LAE) candidate in the immediate foreground of the quasar PSO J158-14 at $z_{\rm QSO}=6.0685$ at a projected distance $\sim29\ {\rm pkpc}$ that is associated with an extremely metal-poor absorption system. This system was found in archival observations of the quasar field with the Very Large Telescope/Multi-Unit Spectroscopic Explorer (VLT/MUSE) and was previously missed in searches of absorption systems using quasar absorption line spectroscopy as it imparts no detectable metal absorption lines on the background quasar spectrum. The detected Ly$α$ emission line at a redshift of $z_{\rm LAE}=6.0323$ is well aligned with the outer edge of the quasar's proximity zone and can plausibly cause its observed damping wing if it is associated with a proximate sub-damped Ly$α$ absorption system with a column density of $\log {N_{\rm HI} / {\rm cm}^{-2}} \approx 19.7$. A $>10$ hour medium-resolution spectrum of the quasar observed with the Magellan/Folded-port InfraRed Echellette (FIRE) and VLT/X-Shooter spectrographs reveals a metallicity constraint of ${\rm [Z/H]} < -3$. Such low metallicity makes this system an extremely metal-poor galaxy candidate and provides an exciting site to study possible signatures of Population III stars.

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Dominika Ďurovčíková, Anna-Christina Eilers, Robert A. Simcoe, Louise Welsh, Romain A. Meyer, Jorryt Matthee, Emma V. Ryan-Weber, Minghao Yue, Harley Katz, Sindhu Satyavolu, George Becker, Frederick B. Davies, Emanuele Paolo Farina. 2025-07-08. An extremely metal-poor Lyman $α$ emitter candidate at $z=6$ revealed through absorption spectroscopy. https://doi.org/10.3847/2041-8213%2Fade71c

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