Fresh insight on cosmic dawn

University astronomers have used the Hubble telescope to uncover galaxies that formed more than 13 billion years ago.

Scientists say that among the newly discovered galaxies is probably the most distant galaxy found to date.

The observations shed new light on the earliest years of cosmic history.

Deep view

The team of Edinburgh scientists, in collaboration with the California Institute of Technology, used the Hubble Space Telescope to observe a tiny patch of sky called the Hubble Ultra Deep Field.

Images created by the study offer the deepest view of the universe seen so far.

Observing the distant galaxies is part of a project to improve scientists’ understanding of the early years of the universe.

This is the first reliable census of galaxies at such an early time in cosmic history, and shows that the number of galaxies has steadily increased with time.

Historic images

Images from the Hubble capture ultraviolet light emitted by the most distant galaxies.

This light is transformed to infrared by the expansion of the universe.

Light takes a very long time to travel from remote objects in space, so the images are effectively looking back in time.

They show the galaxies as they appeared less than 600 million years after the Big Bang.

Cosmic dawn

Six previously unknown galaxies from this era have been uncovered.

Scientists have also been able to rule out a number of tentative identifications of distant galaxies made in previous research.

This supports the idea that the first galaxies did not form in a sudden burst, but gradually assembled their stars, causing the universe to slowly emerge from darkness into a cosmic dawn.

Investigating stars

A major goal of the programme was to determine how rapidly the number of galaxies increased over time in the early universe.

This measure is the key evidence for how quickly galaxies build up their constituent stars.

The results suggest there will be many undiscovered galaxies even deeper in space.

These may be revealed by the James Webb Space Telescope, which is to be launched in 2018.

The team’s new distant galaxy census is scheduled to be published in Astrophysical Journal Letters.

These images give a snapshot of the formation of some of the universe's earliest and most distant galaxies, and will help astronomers piece together events just after the big bang.
Professor James DunlopSchool of Physics and Astronomy