Thanks to our Monte Carlo Lyman-alpha (lya) Radiation Transfer code, McLya, we fitted lya emission profiles from 11 Lyman Break Galaxies observed at medium resolution (R=2000) with FORS2 on the VLT at redshift from 3 to 5, as well as the broad absorption profile of the strongly gravitationally lensed galaxy cB58 at redshift 2.8.
The fitting model is a spherical expanding shell of swept up neutral material surrounding a central starburst. It allows to reproduce with great accuracy all kinds of profiles, ranging from standard asymmetric emission lines to rarer double-peaked profiles, and even broad absorption.
For the first time, constraints on the neutral column density, the dust content, the geometry and the kinematics of the ISM, as well as on the star formation history of the galaxy, are derived from the lya line shape, strength and width, which are consistent with other estimates, when available.
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