Eleven billion years ago, the universe would have been a more extreme and dramatic place. It was a time when star formation peaked and new lights began to shine. Galaxies were at their most active back then.
Framing such a period in detail is not an easy task, but using the power of the Hubble Space Telescope combined with other ground and space observatories, astronomers have produced an incredible picture of what the universe looked like just 3 billion years after the Big Bang.
The image shows 15,000 galaxies, of which 12,000 are actively forming stars whose light comes to us from different moments in time and varying locations in space. As is often the case with astronomical images, this is not just beautiful, it is also extremely useful.
Due to the expansion of the universe, the light of distant galaxies is stretched into redder and redder colors meaning that observing them is only possible using infrared telescopes. These galaxies straddle the gap between the most distant galaxies and their modern counterparts, which we can see with many different wavelengths.
The image is full of data and interesting details. It tells us about the evolution of galaxies – their minor and major changes from internal processes, like supernovae and supermassive black holes, and those from external ones, like collisions and flybys. This is a window into a crucial time for the universe.
Hubble doesn’t only bring its sharp eye, it also brings its ability to see the universe in ultraviolet (UV) light. Young stars are particularly bright at those wavelengths but our planet’s atmosphere is quite good at stopping UV photons. So we need space observatories to provide sensitive observations of the universe in UV.
The image is part of the Hubble Deep UV (HDUV) Legacy Survey and the science behind the image is reported in The Astrophysical Journal Supplement Series. The goal of this survey is to understand the evolution of galaxies during this particular period and also to understand when spiral galaxies began to lose their clumpy appearance and form their central bulges and bars.
Hubble is currently in its 29th year of operations in low-Earth orbit. We don’t know how long it will continue to function but team members believe it could potentially last until the 2040s. Its scientific successor, the James Webb Space Telescope, is scheduled to launch in March 2021.