On the formation of Lyman $\alpha$ emission from resonantly scattered continuum photons of GRB's afterglow

Abstract

We study the formation and evolution of the spectral imprint of resonantly scattered Lyman $\alpha$ photons in the context of GRB's continuum optical afterglow. Based on an analytic model and a complete treatment of all the scatterings using Monte Carlo simulations, we found that the flux of the Ly$\alpha$ emission is mainly contributed by photons which are scattered only once. The flux is of order $10^{-4}$ to $10^{-9}$ relative to the undecayed maximum flux of the transmitted continuum, making the feature negligible but potentially observable. If not obscured by host galaxy's DLA or intergalactic neutral hydrogen, the feature may appear sometime from one hour to several years when the directly transmitted light has faded away.This scattered emission feature can be distinguished from Ly$\alpha$ photons of other origins by its luminosity evolution, and by its gradual narrowing of profile with time. The typical time scale for spectral variance is that of the light crossing time of a hydrogen clump close to the GRB.

29 pages, 13 figures, accepted for publication in ApJ

References in corpus (11)

• The Supernova -- Gamma-Ray Burst Connection
• A glimpse of the end of the dark ages: the gamma-ray burst of 23 April 2009 at redshift 8.3
• GRB 090423 at a redshift of z~8.1
• 3D Lyman-alpha radiation transfer. I. Understanding Lyman-alpha line profile morphologies
• Lyman alpha Resonant Scattering in Young Galaxies - Predictions from Cosmological Simulations
• Lyman-alpha Damping Wing Constraints on Inhomogeneous Reionization
• The Polarization of Scattered Lyman Alpha Radiation Around High-Redshift Galaxies
• A z = 3 Lyman Alpha Blob Associated with a Damped Lyman Alpha System Proximate to its Background Quasar
• Testing Reionization with Gamma Ray Burst Absorption Spectra
• A WENO algorithm for radiative transfer with resonant scattering: the time scale of the Wouthuysen-Field Coupling
• Wouthuysen-Field Coupling in the 21 cm Region Around High Redshift Sources

Cited by in corpus (2)

• Time-Dependent Behavior of Lyman$\alpha$ Photon Transfer in High Redshift Optically Thick Medium
• Effect of Dust on Lyman-alpha Photon Transfer in Optically Thick Halo