High-redshift Lyman-alpha emitters in blank and lensing fields

The early universe is the place where stars first formed and it is the time where the future evolution of present-day galaxies has mostly been determined. As such, this work aims to investigate the conditions in and around early star-forming galaxies in the first billion years of the universe. This is possible thanks to the light emitted by ionized hydrogen atoms (e.g. Lyman α line emission) interacting with the star-forming regions of these young galaxies. In combination with the Lyman α data, I also make use of photometry to gain information on other physical aspects of these objects. In chapter 2, I start by comparing the physical properties of a sample of non-emitting galaxies with a sample of emitters to determine if the emitter population is special in some way compared to the rest of the galaxies. In chapter 3, I compare emitters to each other to determine if some profile shapes of Lyman α emission are inherently different from another family of profiles. In chapter 4, I combine the methods used in chapters 2 and 3 to test whether the profile families I identified earlier have different physical properties compared to each other. Finally, I summarize the differences I found in the conclusions and suggest that more study should happen once deeper and more detailed data becomes available.