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arXiv · 2312.02336

Resolving Clumpy vs. Extended Ly-$α$ In Strongly Lensed, High-Redshift Ly-$α$ Emitters

Alexander Navarre·Gourav Khullar·Matthew Bayliss·Håkon Dahle·Michael Florian·Michael Gladders·Keunho Kim·Riley Owens·Jane Rigby·Joshua Roberson·Keren Sharon·Takatoshi Shibuya·Ryan Walker
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Abstract

We present six strongly gravitationally lensed Ly-$α$ Emitters (LAEs) at $z\sim4-5$ with HST narrowband imaging isolating Ly-$α$. Through complex radiative transfer Ly-$α$ encodes information about the spatial distribution and kinematics of the neutral hydrogen upon which it scatters. We investigate the galaxy properties and Ly-$α$ morphologies of our sample. Many previous studies of high-redshift LAEs have been limited in Ly-$α$ spatial resolution. In this work we take advantage of high-resolution Ly-$α$ imaging boosted by lensing magnification, allowing us to probe sub-galactic scales that are otherwise inaccessible at these redshifts. We use broadband imaging from HST (rest-frame UV) and Spitzer (rest-frame optical) in SED fitting; providing estimates on the stellar masses ($\sim 10^8 - 10^9 M_{\odot}$), stellar population ages ($t_{50} <40$ Myr), and amounts of dust ($A_V \sim 0.1 - 0.6$, statistically consistent with zero). We employ non-parametric star-formation histories to probe the young stellar-populations which create Ly-$α$. We also examine the offsets between the Ly-$α$ and stellar continuum, finding small upper limits of offsets ($< 0.1"$) consistent with studies of low-redshift LAEs; indicating our galaxies are not interacting or merging. Finally, we find a bimodality in our sample's Ly-$α$ morphologies: clumpy and extended. We find a suggestive trend: our LAEs with clumpy Ly-$α$ are generally younger than the LAEs with extended Ly-$α$, suggesting a possible correlation with age.

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Alexander Navarre, Gourav Khullar, Matthew Bayliss, Håkon Dahle, Michael Florian, Michael Gladders, Keunho Kim, Riley Owens, Jane Rigby, Joshua Roberson, Keren Sharon, Takatoshi Shibuya, Ryan Walker. 2023-12-04. Resolving Clumpy vs. Extended Ly-$α$ In Strongly Lensed, High-Redshift Ly-$α$ Emitters. https://arxiv.org/abs/2312.02336

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