European astronomers spotted a very old and distant galaxie, which was surprising considering its maturity. Although it had a smaller amount of dust than other mature galaxies like the Milky Way’s, it still contained many stars and large amounts of metals. The scientists, from Denmark, Sweden, UK, France and Italy, used the Very Large Telescope’s X-shooter Instrument and the Atacama Large Millimeter/submillimeter Array to observe the c. 700 million year-old galaxy. The galaxy was called A 1689-zD1 because its brightness was amplified nine times more by the gravitational lens of Abell 16989,, which lies between the Earth’s young galaxy and the Earth. The rich galaxy cluster Abell 1689. is seen in this view taken by the NASA/ESA Hubble Space Telescope. A large concentration of mass can bend light from distant objects, increasing their brightness and making them more visible. The box contains a 1689-zD1. This picture barely shows it because of its faintness. Image: NASA/ESA. Without the gravitational boost from the galaxy cluster, it would have been difficult to see the glow. What is gravitational lensesing? Gravitational lensing is when light from distant objects is magnified around an object larger than the viewer. Einstein’s theory general relativity predicted gravititational lensing. The Universe’s most massive structures are galaxy clusters. They are so strong that their gravitational forces can warp spacetime. Researchers claimed that we could see distant galaxies when they were at only 5% of their current age. The galaxy is very far from us and its light takes many billions of years to reach. This system is relatively small and less luminescent than many other objects studied in this early stage of the Universe. It therefore makes it a typical example for a galaxy. This galaxy is observed in the same way it was at the time of reionization when first stars created a vast and transparent universe and ended the long stagnation that had been ailing the Dark Ages. Precocious and young galaxy. Scientists expected that A 1689-zD1 would look like a new system. The discovery of abundant interstellar dust, and the rich chemical complexity it contained surprised them. Associate Professor Darach Watson from the University of Copenhagen was the study leader. He said, “After verifying the distance of the galaxy using the VLT. It had been previously observed by ALMA. Although we didn’t anticipate finding much, we were quite surprised when we realized that ALMA had observed the galaxy. It would be surprising to find it had heavier chemical elements at this young age – any heavier than hydrogen or helium, which is what astronomy calls metals. They are created deep within stars, and then scattered when they explode. To produce large amounts of heavy elements like carbon, nitrogen and oxygen this process must be repeated several times. The young galaxy was emitting significant amounts of far-infrared radiation, which suggests it has already formed many stars as well as substantial quantities of metals. Kirsten Knudsen from Chalmers University of Technology, Sweden was the co-author. She said: “This amazing dusty galaxy appears to have been in an epoch of starburst incredibly quickly before entering a declining state of star formation. ALMA’s future capabilities will allow us to discover more galaxies similar to this one, and to learn what drives them to become stars. Citation: Darach Watson and Lise Christensen. Johan Richard. Anna Gallazzi. Michal Jerzy Michalowski. European Southern Observatory.
