Galaxy clusters are some of the most massive and largest structures that can be found in the Universe. A new image from the NASA/ESA Hubble Space Telescope shows one of these structures — the massive galaxy cluster RXC J0142.9+4438, which is located approximately 4 billion light-years away in the constellation Andromeda. Astronomers estimate RXC J0142.9+4438 has a mass of 9*1014 solar masses.
This Hubble image shows the galaxy cluster RXC J0142.9+4438. Image credit: NASA / ESA / Hubble / RELICS.
Galaxy clusters are some of the most interesting objects in the cosmos. They can contain thousands of galaxies all held together by the glue of gravity.
At one point in time they were believed to be the largest structures in the Universe — until they were usurped in the 1980s by the discovery of superclusters, which typically contain dozens of galaxy clusters and groups and span hundreds of millions of light-years.
However, clusters do have one thing to cling on to; superclusters are not held together by gravity, so galaxy clusters still retain the title of the biggest structures in the Universe bound by gravity.
In the 1930s, astrophysicists realized that the visible component of galaxy clusters represents only a tiny fraction of the total mass; about 80% of the matter is invisible, the so-called ‘dark matter.’
Not only are galaxy clusters ideal subjects for the study of this type of matter, but they also allow the study of farther-flung galaxies.
Their immense gravitational influence means they distort the spacetime around them, causing them to act like giant cosmic lenses.
The light of background galaxies is warped and magnified as it passes through the galaxy cluster, allowing astronomers insight into the distant — and therefore early — Universe.
This image of RXC J0142.9+4438 was taken by Hubble’s Advanced Camera for Surveys (ACS) and Wide-Field Camera 3 (WFC3) as part of an extensive observing program called Reionization Lensing Cluster Survey (RELICS).
RELICS imaged 41 giant galaxy clusters over the course of 390 Hubble orbits, aiming to find the brightest distant galaxies.
Studying these galaxies in more detail with both current telescopes and the forthcoming James Webb Space Telescope will hopefully tell us more about our cosmic origins.
