The cosmic evolution of star-forming galaxies

Our Universe is rather quiet now, but when it was half of its current age it was positively booming with star formation and the light from accretion onto black holes. In star-forming galaxies, short-lived massive stars pump out large amounts of ultraviolet light. We can track the history of star-formation over the Universe's history by measuring the space density of ultraviolet-emitting galaxies (how many there are per cubic megaparsec) as a function of redshift and luminosity. Ultraviolet radiation at wavelengths shorter than 350 nanometres is absorbed in the Earth's atmosphere. At high redshift, the ultraviolet emission is shifted into the optical, and ground-based telescopes do a grand job. But for the second half of the Universe's history, the measurements need ultraviolet measurements from Space. MSSL has built two ultraviolet telescopes that are in operation in space right now: the Optical/UV Monitor telescope onboard the European Space Agency's XMM-Newton observatory, and the Ultraviolet/Optical Telescope onboard NASA's Neil Gehrels Swift Observatory. This project is to use ultraviolet data from these two telescopes, together with a host of supporting multi-wavelength observations, to study the properties and evolution of star forming galaxies during their great decline, between redshift 1, when the Universe was about half of its current age, and the present day.