An astronomer from Queen Mary University of London is part of a team that has discovered new insights into the birth and death of the very first stars in the Universe – by turning an entire galaxy cluster into a cosmic lens – 2,300 light years in diameter.

The team has been able to peer through the eons at an unexpectedly huge mass of glowing stardust in a galaxy seen when the Universe was only 600million years old, just 4% of its present age.

The ground-based Alma array in the Atacama desert was just the first step in penetrating the furthest distances in the observable Universe. The secret was to turn an entire galaxy cluster called Pandora’s Cluster into a huge telescope.

Using a phenomenon called gravitational lensing, this mega-lens bent the light and magnified the more distant galaxy 1.8 times.

Pandora's cluster – the "lens"

Dr David Quénard from QMUL’s School of Physics and Astronomy said: “It’s impressive that Alma was able to detect such a faint object at such a huge distance – this indicates how sensitive this telescope is at low resolution.”

Dust revelations

And it’s the discovery of all that dust that is exciting scientists.

Dr Nicolas Laporte from University College London, said: “The detection of so much dust indicates early supernovae must have already polluted this galaxy.”

Cosmic dust is composed of silicon, carbon, and aluminium, in grains as small as a millionth of a centimetre. These grains are forged inside stars and are scattered across the cosmos when the stars die, most spectacularly in supernova explosions.

Radio telescope antennas of the Alma ( Atacama Large Millimeter/submillimeter Array) project, in the Chajnantor plateau, Atacama desert, some 1500 km north of Santiago

There’s now plenty of dust to build stars, planets and even complex molecules but in the early Universe it was scarce. Any clues to the birth of the first supernovae help scientists date the “cosmic dawn” when the universe was bathed in light for the first time.

Early galaxy

The team estimates that the far distant galaxy A2744_YD4 contained an amount of dust equivalent to 6million times the mass of our Sun. The team also found that stars were forming at a rate of 20 solar masses per year – compared to just one solar mass per year in our own Milky Way.

Co-author Prof Richard Ellis from UCL, said: “It does shed light on how quickly the dust in A2744_YD4 formed. Remarkably, the required time is only about 200 million years – so we are witnessing this galaxy shortly after its formation.”

This means that significant star formation began approximately 200 million years before the epoch at which the galaxy is being observed.

The findings are published in The Astrophysical Journal Letters .

The first antenna of the Alma (Atacama Large Millimetre/Submillimetre Array) project

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