The cosmic evolution of star-forming galaxies

我们的宇宙现在相当安静，但当它是现在年龄的一半时，它正因恒星形成和黑洞吸积的光而蓬勃发展。在形成恒星的星系中，寿命短的大质量恒星会释放出大量的紫外线。我们可以通过测量发射紫外线的星系的空间密度（每立方兆秒差距有多少个星系）作为红移和光度的函数来追踪宇宙历史上恒星形成的历史。波长短于350纳米的紫外线辐射被地球大气层吸收。在高红移时，紫外线发射被转移到光学上，地面望远镜做了一个伟大的工作。但对于宇宙后半段的历史，测量需要来自太空的紫外线测量。MSSL已经建造了两个正在太空中运行的紫外望远镜：欧洲航天局xmm -牛顿天文台上的光学/紫外监测望远镜，以及美国宇航局尼尔·格雷斯·斯威夫特天文台上的紫外/光学望远镜。这个项目是利用这两个望远镜的紫外线数据，以及大量支持的多波长观测，来研究恒星形成星系在红移1（宇宙大约是现在年龄的一半）和现在之间的大衰退期间的特性和演化。

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.