James Webb Space Telescope captures ‘baby years’ of huge galaxy cluster

Webb was able to image this protocluster as it was billions of years ago because light takes a lot of time to travel through space. Since light takes billions of years to travel the distance from the protocluster to us, we are seeing it as it was billions of years ago.

The results of the study on the protocluster have been published in the peer-reviewed Astrophysical Journal Letters.

“This is a very special, unique site of accelerated galaxy evolution, and Webb gave us the unprecedented ability to measure the velocities of these seven galaxies and confidently confirm that they are bound together in a protocluster,” said Takahiro Morishita, lead author of the study, in a press statement.

The galaxies were moving withing a halo of dark matter at speeds of nearly one thousand kilometres per second. But despite this, the spectral data from Webb allowed astronomers to model and map the future development of the gathering group, all the way to our time today.

In order to be able to see this distant group, astronomers took advantage of a phenomenon known as gravitational lensing. Galaxy clusters are some of the most massive cosmic objects that exist. They have such high concentrations of mass that they can warp the fabric of spacetime.

Sometimes, they warp the spacetime fabric in such a way that they create a kind of “lens” that bends light. This gravity lens can help “magnify” the objects behind it, making it easier for astronomers to observe distant cosmic objects.