In 12 billion years, our universe was still young and at the peak of its star-making potential. Recently, a team of researchers trained NASA’s Hubble Space Telescope on objects during that period, and the results were quite startling.
Six massive galaxies were “dead” – galaxies that stopped producing new stars.
In the words of Kate Whitaker, who led the research and is an astronomy professor at the University of Massachusetts-Amherst, most massive galaxies in our universe formed when it was still young, right after the big bang.
For some mysterious reason, the galaxies found by Hubble have stopped making stars.
It has turned out that these galaxies have simply run out of cold hydrogen – the fuel necessary for forming new stars – early in their lives. In a study published by Whitaker and her fellow researchers in the journal Nature, the researchers uncover new information about how the universe developed.
Images showing two of the six, massive “dead” galaxies. Credits: Joseph DePasquale/NASA
Galaxies are essentially doomed without the cold hydrogen necessary to kickstart star formation. Nevertheless, the reason why cold hydrogen was lost is still a mystery that researchers are trying to solve.
Whitaker suggests a supermassive black hole at the galaxy’s center may have heated up all the gas, preventing it from forming stars, or it could have been expelled from the galaxy. The gas could have simply run out, and they may not have had access to fresh gas.
The study of galaxies and further observations are expected to provide answers.
It was challenging to find galaxies that were far away in both distance and time. Using the Hubble Space telescope, they used a technique called gravitational lensing to locate the galaxies. The Atacama Large Millimeter/Submillimeter Array in Chile was used to detect whether galaxies contained cold dust, a proxy for cold hydrogen.