Dark-ages reionization and galaxy formation simulation XX. The Ly alpha IGM transmission properties and environment of bright galaxies during the epoch of reionization

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  • Yuxiang Qin
  • J. Stuart B. Wyithe
  • Pascal A. Oesch
  • Garth D. Illingworth
  • Ecaterina Leonova
  • Simon J. Mutch
  • Rohan P. Naidu

The highly neutral intergalactic medium (IGM) during the epoch of reionization (EoR) is expected to suppress Ly alpha emission with damping-wing absorption, causing nearly no Ly alpha detection from star-forming galaxies at z similar to 8. However, spectroscopic observations of the four brightest galaxies (H-160 similar to 25 mag) at these redshifts do reveal prominent Ly alpha line, suggesting locally ionized IGM. In this paper, we explore the Ly alpha IGM transmission and environment of bright galaxies during the EoR using the Meraxes semi-analytic model. We find brighter galaxies to be less affected by damping-wing absorption as they are effective at ionizing surrounding neutral hydrogen. Specifically, the brightest sources (H-160 less than or similar to 25.5 mag) lie in the largest ionized regions in our simulation, and have low attenuation of their Ly alpha from the IGM (optical depth = 2-5 neighbours within 2 arcmin x 2 arcmin are similar to 2-3 times more likely to show Ly alpha emission. JWST will discover an order of magnitude more neighbours, revealing greater than or similar to 50 galaxies in the largest ionizing bubbles and facilitating direct study of reionization morphology.

Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society
Volume510
Issue number3
Pages (from-to)3858-3866
Number of pages9
ISSN0035-8711
DOIs
Publication statusPublished - 12 Jan 2022

    Research areas

  • cosmology: theory, dark ages, reionization, first stars, diffuse radiation, early Universe, galaxies: high-redshift, intergalactic medium, SIMILAR-TO 7, EQUIVALENT-WIDTH DISTRIBUTION, TEXAS SPECTROSCOPIC SEARCH, UV LUMINOSITY FUNCTIONS, LYMAN-ALPHA, INTERGALACTIC MEDIUM, COSMIC REIONIZATION, ESCAPE FRACTION, BACKGROUND FLUCTUATIONS, OPACITY FLUCTUATIONS

ID: 303442582