2025/10/21 by Meredith Neyer, Aaron Smith, Neyer, Meredith +11 · 1 voice
Physics and Astronomy · #Galaxies: Formation, Evolution, Phenomena #Radio Astronomy Observations and Technology #Astronomy and Astrophysical Research
paper · doi:10.33232/001c.160756
openalex created_date 2025/10/24 · openalex publication_date 2026/04/17 · openalex updated_date 2026/07/31
We use the THESAN radiation-hydrodynamics simulations to investigate how Lyman- <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>α</mml:mi> </mml:math> emitters (LAEs) trace ionized bubble sizes during the Epoch of Reionization. We generate realistic LAE catalogs by combining accurate intrinsic Ly <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>α</mml:mi> </mml:math> production and intergalactic transmission with an empirical model for dust absorption and gas outflows. By calibrating to observationally-constrained Ly <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>α</mml:mi> </mml:math> luminosity functions, we reproduce the rapid decline in Ly <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>α</mml:mi> </mml:math> visibility toward higher redshifts while revealing mild tensions in LAE fractions near the end of reionization. Before the midpoint of reionization, galaxies within larger line-of-sight bubbles ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo>≳</mml:mo> <mml:mn>10</mml:mn> </mml:mrow> </mml:math> cMpc) have higher observed Ly <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>α</mml:mi> </mml:math> luminosity and equivalent width (EW), demonstrating that the evolving LAE fraction provides a practical statistical tracer for bubble size. These correlations weaken as percolation progresses and the IGM becomes increasingly ionized. In LAE selected samples with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mi>L</mml:mi> <mml:mrow> <mml:mtext mathvariant="normal">Ly</mml:mtext> <mml:mi>α</mml:mi> </mml:mrow> </mml:msub> <mml:mo>></mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>41.5</mml:mn> </mml:msup> <mml:mspace width="0.222em"/> <mml:msup> <mml:mtext mathvariant="normal">erg s</mml:mtext> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> , Ly <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>α</mml:mi> </mml:math> properties correlate with bubble size more strongly than UV magnitude, especially at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mi>z</mml:mi> <mml:mo>≳</mml:mo> <mml:mn>7</mml:mn> </mml:mrow> </mml:math> . This simulation-based framework maps LAE selections to bubble-size statistics, clarifies biases in more idealized models, and will supply public catalogs to interpret current and forthcoming JWST and narrow-band LAE surveys in terms of the evolving topology of reionization.