The escape of Lya photons in star-forming galaxies
Abstract
Our knowledge of the very high redshift Universe heavily depends upon the observation of the Lyman-alpha {Lya} emission line for both spectroscopic confirmation and often the actual discovery of galaxies at very high redshifts. However, no comprehensive study of the astrophysics behind the Lya production, transport, and escape fraction has so far been made, since the required supplementary observations are redshifted to inaccessible wavelengths for cosmological populations. At z 0, such studies can be undertaken, but the number of known Lya emitting galaxies is extremely small and observationally biased.With the aim of characterizing the physics of Lya escape from galaxies, our group has undertaken a major effort to followup a new well-defined sample of GALEX-selected z 0.3 Lya emitters. Here, we propose to obtain FUV COS-G160M spectroscopy of 25 GALEX star-forming Lya emitters for which we have already measured gas metallicity, nebular extinction, escape fraction of Lya photons, and stellar masses. The COS spectra will provide the shape of the Lya profile, a fundamental diagnostic of the physical conditions of the ISM, since it encodes crucial information about the kinematics, column density, and dust content of the neutral gas. By investigating the physical mechanisms driving the Lya output in a well-defined sample of low-z Lya emitters, the proposed study will provide us with the necessary knowledge to interpret the observations in the more distant universe.
- Publication:
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HST Proposal
- Pub Date:
- September 2010
- Bibcode:
- 2010hst..prop12269S