Spatially Resolved Spectroscopy of Faint Star-Forming Galaxies & their Environments in the High Redshift Universe

Abstract

This thesis is concerned with the spectroscopic observations of distant galaxies, 1 < z < 5. The galaxies presented here are intrinsically faint such that their ux is dominated by ordinary star formation rather than galaxy-galaxy merging and/or strong nuclear activity. Such studies are normally untenable owing to the faintness of this type of galaxy. The approach used in this work is to select objects gravitationally-lensed by massive foreground clusters of galaxies. Cluster lensing boosts galaxy brightnesses by factors of ten or more whilst simultaneously magnifying the object size, allowing for the detailed study of ordinary objects at high redshift. We present spectroscopic data for a strongly-lensed galaxy at z = 0:79 from which we measure the physical conditions in the interstellar medium and characterise the star formation history/ activity. Signicant spatial variations in its star formation activity and metallicity are apparent. We also present evidence for an overdensity of neutral hydrogen in the vicinity of a galaxy at z = 4:9, which we interpret as gas infall onto an object which still has yet to accumulate the bulk of its gas mass. A study of the eld of the lensing cluster Abell 1689 is presented, which utilises the excellent spatial resolution of the G800L grism on board the Hubble Space Telescope. Observations of two Einstein Ring galaxies at z 2 􀀀 3 are also presented, with the spectrum of one of these displaying evidence for large scale gaseous out ows. Studies such as these are crucial for understanding the physics governing young galaxies as they form. These results are discussed in the context of the current paradigm of galaxy evolution.