We present a new flexible Bayesian framework for directly inferring the fraction of neutral hydrogen in the intergalactic medium (IGM) during the Epoch of Reionization (EoR, z ∼ 6-10) from detections and non-detections of Lyman Alpha (Lyα) emission from Lyman Break galaxies (LBGs). Our framework combines sophisticated reionization simulations with empirical models of the interstellar medium (ISM) radiative transfer effects on Lyα. We assert that the Lyα line profile emerging from the ISM has an important impact on the resulting transmission of photons through the IGM, and that these line profiles depend on galaxy properties. We model this effect by considering the peak velocity offset of Lyα lines from host galaxies' systemic redshifts, which are empirically correlated with UV luminosity and redshift (or halo mass at fixed redshift). We use our framework on the sample of LBGs presented in Pentericci et al. and infer a global neutral fraction at z ∼ 7 of , consistent with other robust probes of the EoR and confirming that reionization is ongoing ∼700 Myr after the Big Bang. We show that using the full distribution of Lyα equivalent width detections and upper limits from LBGs places tighter constraints on the evolving IGM than the standard Lyα emitter fraction, and that larger samples are within reach of deep spectroscopic surveys of gravitationally lensed fields and James Webb Space Telescope NIRSpec.

The Universe Is Reionizing at z ∼ 7: Bayesian Inference of the IGM Neutral Fraction Using Lyα Emission from Galaxies

Treu, Tommaso;Dijkstra, Mark;Mesinger, Andrei;Trenti, Michele;Pentericci, Laura;Vanzella, Eros
2018

Abstract

We present a new flexible Bayesian framework for directly inferring the fraction of neutral hydrogen in the intergalactic medium (IGM) during the Epoch of Reionization (EoR, z ∼ 6-10) from detections and non-detections of Lyman Alpha (Lyα) emission from Lyman Break galaxies (LBGs). Our framework combines sophisticated reionization simulations with empirical models of the interstellar medium (ISM) radiative transfer effects on Lyα. We assert that the Lyα line profile emerging from the ISM has an important impact on the resulting transmission of photons through the IGM, and that these line profiles depend on galaxy properties. We model this effect by considering the peak velocity offset of Lyα lines from host galaxies' systemic redshifts, which are empirically correlated with UV luminosity and redshift (or halo mass at fixed redshift). We use our framework on the sample of LBGs presented in Pentericci et al. and infer a global neutral fraction at z ∼ 7 of , consistent with other robust probes of the EoR and confirming that reionization is ongoing ∼700 Myr after the Big Bang. We show that using the full distribution of Lyα equivalent width detections and upper limits from LBGs places tighter constraints on the evolving IGM than the standard Lyα emitter fraction, and that larger samples are within reach of deep spectroscopic surveys of gravitationally lensed fields and James Webb Space Telescope NIRSpec.
2018
Settore FIS/05 - Astronomia e Astrofisica
dark ages, reionization, first stars; galaxies: evolution; galaxies: high redshift; intergalactic medium; Astronomy and Astrophysics; Space and Planetary Science
File in questo prodotto:
File Dimensione Formato  
Mason_2018_ApJ_856_2.pdf

accesso aperto

Tipologia: Published version
Licenza: Creative Commons
Dimensione 1.62 MB
Formato Adobe PDF
1.62 MB Adobe PDF
Mason_1709.05356.pdf

Accesso chiuso

Tipologia: Submitted version (pre-print)
Licenza: Non pubblico
Dimensione 1.08 MB
Formato Adobe PDF
1.08 MB Adobe PDF   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/77891
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 221
  • ???jsp.display-item.citation.isi??? 213
social impact