Paper

{
  "raw_xml": "<entry>\n    <id>http://arxiv.org/abs/2603.04517v1</id>\n    <title>MXDFz4.4: A LyC emitter 250Myr after the epoch of reionization and a first test of Ly-alpha morphology as a tracer of LyC escape at high redshift</title>\n    <updated>2026-03-04T19:05:20Z</updated>\n    <link href='https://arxiv.org/abs/2603.04517v1' rel='alternate' type='text/html'/>\n    <link href='https://arxiv.org/pdf/2603.04517v1' rel='related' title='pdf' type='application/pdf'/>\n    <summary>Assessing the contribution of ionizing sources to cosmic reionization is a central goal of extragalactic astrophysics. Understanding and quantifying ionizing escape remains challenging near the epoch of reionization. We present the highest-redshift Lyman continuum (LyC) emitter detected to date, MXDFz4.4 at z=4.442 in the MUSE eXtremely Deep Field, observed only ~0.25Gyr after the end of reionization. A high confidence Ly-alpha line confirms the redshift. LyC flux is detected at 10.3sigma in the F435W filter with a flux of 4.2+/-0.5nJy, corresponding to a flux measurement at 8.0sigma. After correcting for the intrinsic production of LyC photons and the IGM opacity at z=4.44, we derive high escape fractions, ranging from 50 - 100%. We apply established low-redshift tracers of LyC escape and, for the first time at high redshift, promising Ly-alpha morphological tracers such as the halo fraction. SED fitting indicates the presence of a recent burst of star formation; we explore its impact on the production and escape of ionizing photons. Ly-alpha-based tracers of LyC escape reveal a complex scenario in which the recent burst strong influences LyC production and escape, combined with a more evolved stellar population. This interpretation is supported by UV diagnostics, including the star formation rate surface density and sSFR. Our results provide cautious support for the Ly-alpha halo fraction as a LyC escape tracer at high redshift. Considering the burst-driven enhancement in LyC production and escape, we conclude that stochastic star formation in the early Universe likely plays a significant role in the contribution of galaxies to cosmic reionization.</summary>\n    <category scheme='http://arxiv.org/schemas/atom' term='astro-ph.GA'/>\n    <published>2026-03-04T19:05:20Z</published>\n    <arxiv:comment>24 pages, 14 figures, 2 tables, 2 appendices. Submitted to ApJ</arxiv:comment>\n    <arxiv:primary_category term='astro-ph.GA'/>\n    <author>\n      <name>Ilias Goovaerts</name>\n    </author>\n    <author>\n      <name>Marc Rafelski</name>\n    </author>\n    <author>\n      <name>Alexander Beckett</name>\n    </author>\n    <author>\n      <name>Grecco Oyarzùn</name>\n    </author>\n    <author>\n      <name>Annalisa Citro</name>\n    </author>\n    <author>\n      <name>Farhanul Hasan</name>\n    </author>\n    <author>\n      <name>Kalina V Nedkova</name>\n    </author>\n    <author>\n      <name>Calum Hawcroft</name>\n    </author>\n    <author>\n      <name>Anton M Koekemoer</name>\n    </author>\n    <author>\n      <name>Mitchell Revalski</name>\n    </author>\n    <author>\n      <name>Matthew J Hayes</name>\n    </author>\n    <author>\n      <name>Claudia Scarlata</name>\n    </author>\n    <author>\n      <name>Ray A Lucas</name>\n    </author>\n    <author>\n      <name>Norman A Grogin</name>\n    </author>\n    <author>\n      <name>David V Stark</name>\n    </author>\n    <author>\n      <name>Paolo Suin</name>\n    </author>\n    <author>\n      <name>Nor Pirzkal</name>\n    </author>\n  </entry>"
}