Effects of photon trapping on the Lyman-alpha properties of star-forming galaxies

Abstract

Recent observations show that a large number of Lyman-alpha emitters (LAEs) at high redshift z >= 3 have unusually high Lya equivalent widths (EW > 400 angstrom). However, the origin of these high EWs is an open question. Here, we investigate the impacts of photon trapping on the Lya EW and other properties by tracking the Lya radiative transfer in spherical galactic clouds. We find that the delayed escape of the Lya photons can change the Lya properties significantly. During the transition phase from optically thick to optically thin where the Lya photons can escape simultaneously, the EW can be boosted to ~ 1000 angstrom, the Lya luminosity can be increased by a factor of a few, and the line profile can be significantly broadened. The boost factor appears to depend on the galaxy properties such as mass and star formation rate and timescale, therefore future investigation combing 3D Lya RT calculations with cosmological simulations of galaxy formation and evolution is needed to fully understand the Lya properties of early star-forming galaxies.

7 pages, 7 figures, accepted for publication in MNRAS

References in corpus (10)

• The Subaru/XMM-Newton Deep Survey (SXDS). IV. Evolution of Lya Emitters from z=3.1 to 5.7 in the 1 deg^2 Field: Luminosity Functions and AGN
• The redshift dependence of the structure of massive LCDM halos
• Ly-alpha Emission-Line Galaxies at z = 3.1 in the Extended Chandra Deep Field South
• A galaxy at a redshift z = 6.96
• Radiative transfer simulations of cosmic reionization I: methodology and initial results
• Gas Motion Study of Lya Emitters at z~2 Using UV and Optical Spectral Lines
• On the (non-)enhancement of the Lyman α equivalent width by a multiphase interstellar medium
• Modeling the Dust Properties of z ~ 6 Quasars with ART^2 -- All-wavelength Radiative Transfer with Adaptive Refinement Tree
• A photometric survey for Lyalpha-HeII dual emitters: Searching for Population III stars in high-redshift galaxies
• A Ly-alpha Emitter with an Extremely Large Rest-frame Equivalent Width of ~900A at z=6.5: A Candidate of Population III-dominated Galaxy?

Cited by in corpus (5)

• The LyA-LyC Connection: Evidence for an Enhanced Contribution of UV-faint Galaxies to Cosmic Reionization
• First Spectroscopic Evidence for High Ionization State and Low Oxygen Abundance in Lya Emitters
• Lyman Alpha and MgII as Probes of Galaxies and their Environments
• Upper limits on the mass and luminosity of Population III-dominated galaxies
• Angular momentum loss of primordial gas in Lyman-alpha radiation field