Large-scale filaments and the intergalactic medium

Matter in the current-day Universe has formed an intricate pattern of nodes and sheet-like walls, connected by filaments. This is known as the cosmic web. The galaxies are preferentially formed within these filaments. All the diffuse gas outside galaxies is referred to as the intergalactic medium (IGM). The IGM in large-scale filaments consists mostly of hydrogen and helium and affects the evolution of galaxies. Additionally, gas inflowing onto the galaxies from the filaments can be used to power star formation and it is therefore important to study the properties of the IGM. By measuring the amount of neutral gas in the IGM, it becomes possible to constrain the temperature and ionization state of the IGM. However, the emission from this gas is very faint. This thesis explores the potential of current and upcoming surveys to measure such emission from cosmic web filaments . By using simulations, an estimate is made for the strength of the IGM signal. Consequently, the requirements to be able to map the ultraviolet emission from the cosmic web with a space telescope are determined. Furthermore, for radio emission from the IGM, a method is presented where the location of the filaments is first determined from the distribution of galaxies, after which the faint signal from the IGM can be measured by integrating along the filament. This work shows that a number of current and upcoming radio telescopes will be sensitive enough to detect this integrated signal.