The Bottom of the Iceberg: Faint z~2 Galaxies and the Enrichment of the IGM
Abstract
Galaxies at z 2-3 formed stars rapidly and expelled large quantities of gas to great distances via powerful galactic outflows. Much has been learned about interactions between star-forming galaxies and the IGM from our joint galaxy/QSO survey in which high quality spectra of bright QSOs are used to sample the gas around foreground galaxies. With this proposal we extend that survey to large numbers of significantly fainter galaxies, via a spectroscopic WFC3/IR grism survey of 15 QSO fields and their surrounding foreground galaxies. This survey takes advantage of the grism's optimal sensitivity to high equivalent width emission lines from compact sources. It will encompass 1500 galaxies at 1.5<z<2.3, 1000 of which are fainter than the current survey limit and 2/3 of which do not appear in our photometric catalogs because of incompleteness. In only 30 orbits {and in a single step, rather than through the construction of an HST-based photometric catalog followed by spectroscopy} this sample will increase the number of spectroscopically confirmed galaxies near QSO sightlines by up to a factor of 6, and will allow a study of the impact of these numerous faint galaxies on the IGM. The grism data will also provide spatially resolved measurements of the sizes of the line emitting regions, for studies of the relationship between the star formation rate density and the strength of galactic outflows, for the first time at z 2. Thus the survey will address two outstanding problems in the study of galactic outflows at high redshift: the lack of dynamic range in mass, luminosity and metallicity in the sample, and the lack of spatially resolved measurements of line emission.
- Publication:
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HST Proposal
- Pub Date:
- October 2011
- Bibcode:
- 2011hst..prop12471E