Profiles of Lyman\\alpha\\ Emission Lines

Abstract

We present the results of the observations of the Ly\\alpha\\ line profiles of\n91 emission-line galaxies at z=3.1 with the spectral resolution of\n\\lambda/\\delta\\lambda (FWHM) = 1700, or 180 km/s. A significant fraction, ~50%\nof the observed objects show the characteristic double peaks in their Ly\\alpha\nprofile. The red peak is much stronger than the blue one for most of the cases.\nThe red peaks themselves also show weak but significant asymmetry and their\nwidths are correlated with the velocity separation of the red and the blue\npeaks, which implies that the peaks are not isolated multiple components with\ndifferent velocities but the parts of the single line which is modified by the\nabsorption and/or scattering by the associated neutral hydrogen gas. The\ncharacteristic profile can be naturally explained by the scattering in the\nexpanding shell of neutral hydrogen surrounding the Ly\\alpha\\ emitting region\nwhile the attenuation by the inter-galactic medium should also be considered.\nOur results suggest that the star-formation in these Ly\\alpha\\ emitters are\ndominated by the young burst-like events which produce the intrinsic Ly\\alpha\\\nemission as well as the gas outflow.\n