Crucial Factors for Lyα Transmission in the Reionizing Intergalactic Medium: Infall Motion, H ii Bubble Size, and Self-shielded Systems - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Astrophys.J. Année : 2021

Crucial Factors for Lyα Transmission in the Reionizing Intergalactic Medium: Infall Motion, H ii Bubble Size, and Self-shielded Systems

Hyunbae Park
  • Fonction : Auteur
Intae Jung
  • Fonction : Auteur
Hyunmi Song
  • Fonction : Auteur
Pierre Ocvirk
Paul R. Shapiro
  • Fonction : Auteur
Taha Dawoodbhoy
Ilian T. Iliev
  • Fonction : Auteur
Kyungjin Ahn
  • Fonction : Auteur
Michele Bianco
  • Fonction : Auteur
Hyo Jeong Kim
  • Fonction : Auteur

Résumé

Using the CoDa II simulation, we study the Lyα transmissivity of the intergalactic medium (IGM) during reionization. At z > 6, a typical galaxy without an active galactic nucleus fails to form a proximity zone around itself due to the overdensity of the surrounding IGM. The gravitational infall motion in the IGM makes the resonance absorption extend to the red side of Lyα, suppressing the transmission up to roughly the circular velocity of the galaxy. In some sight lines, an optically thin blob generated by a supernova in a neighboring galaxy results in a peak feature, which can be mistaken for a blue peak. Redward of the resonance absorption, the damping-wing opacity correlates with the global IGM neutral fraction and the UV magnitude of the source galaxy. Brighter galaxies tend to suffer lower opacity because they tend to reside in larger H ii regions, and the surrounding IGM transmits redder photons, which are less susceptible to attenuation, owing to stronger infall velocity. The H ii regions are highly nonspherical, causing both sight-line-to-sight-line and galaxy-to-galaxy variation in opacity. Also, self-shielded systems within H ii regions strongly attenuate the emission for certain sight lines. All these factors add to the transmissivity variation, requiring a large sample size to constrain the average transmission. The variation is largest for fainter galaxies at higher redshift. The 68% range of the transmissivity is similar to or greater than the median for galaxies with M $_{UV}$ ≥ −21 at z ≥ 7, implying that more than a hundred galaxies would be needed to measure the transmission to 10% accuracy.

Dates et versions

hal-03262710 , version 1 (16-06-2021)

Identifiants

Citer

Hyunbae Park, Intae Jung, Hyunmi Song, Pierre Ocvirk, Paul R. Shapiro, et al.. Crucial Factors for Lyα Transmission in the Reionizing Intergalactic Medium: Infall Motion, H ii Bubble Size, and Self-shielded Systems. Astrophys.J., 2021, 922 (2), pp.263. ⟨10.3847/1538-4357/ac2f4b⟩. ⟨hal-03262710⟩
32 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More