NASA uses gravitational lensing to find 'dead' galaxies from the early universe

As NASA recounts, when the universe was roughly three billion years old, it was in its prime formation phase. Yet oddly enough, the six distant, massive galaxies recently discovered were no longer making stars as they’d depleted all of their cold hydrogen gas, a key fuel source.
https://www.techspot.com/news/91441-nasa-uses-gravitational-lensing-find-dead-galaxies-early.html?utm_source=dlvr.it&utm_medium=blogger