Open AccessProbing reionization with Lyman α emission lines
Author(s) -
Santos Michael R.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.07594.x
Subject(s) - physics , astrophysics , galaxy , reionization , galactic halo , astronomy , redshift , halo , active galactic nucleus
Lyman α emission from high‐redshift galaxies may be a powerful probe of the ionization history of the intergalactic medium (IGM) at z > 6 ; the observed Lyman α emission line is sensitive to the IGM hydrogen neutral fraction over the range 0.1–1. We present calculations of observed Lyman α emission lines from z > 6 galaxies, illustrating the effect of varying the many free parameters associated with the emitting galaxy, its halo and the IGM around the galaxy. In particular, we use a dynamic model of the IGM that includes the effect of IGM infall toward the emitting galaxy. Galactic winds may play a crucial role in determining observed Lyman α line fluxes. We compare our model predictions with observations of two z = 6.5 galaxies and conclude that, if galactic winds are allowed for, existing observations place no constraint on the neutral fraction of the IGM at z = 6.5 . Future infrared observations will constrain the importance of galactic winds; if winds are unimportant for the observed z = 6.5 galaxies, our models suggest that the IGM neutral fraction at z = 6.5 is ≲0.1 .