SDSS J1226+2152, a huge galaxy cluster in the constellation of Coma Berenices, acts as a strong gravitational lens, causing light from distant galaxies to bend around it.
This Hubble image shows the galaxy cluster SDSS J1226+2152. Image credit: NASA / ESA / CSA / Webb / J. Rigby / JWST TEMPLATES Team.
Galaxy clusters contain thousands of galaxies of all ages, shapes and sizes. Typically, they have a mass of about one million billion times the mass of the Sun.
At one point in time galaxy clusters 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.
Albert Einstein predicted in his theory of general relativity that massive objects will deform the fabric of space itself.
When light passes one of these objects, such as a galaxy cluster, its path is changed slightly.
Known as gravitational lensing, this effect is only visible in rare cases and only the best telescopes can observe the related phenomena.
“SDSS J1226+2152 is distorting the images of distant background galaxies into streaks and smears of light,” Webb astronomers said in a statement.
“This is a spectacular example of gravitational lensing, a phenomenon which occurs when a massive celestial object such as a galaxy cluster deforms spacetime and causes the path of light from more distant galaxies to be deflected, almost as if a monumental lens was redirecting it.”
“One of the most notable lensed galaxies in the field of SDSS J1226+2152 is named SGAS J12265.3+215220.”
“In this image, it’s the innermost lensed galaxy, just above and to the right of the central galaxy.”
“This lies far beyond the foreground cluster in distance, giving us a view into the galaxy roughly two billion years after the big bang.”
The astronomers are now using this eagerly-awaited hoard of bright, gravitationally-lensed galaxies from Webb to explore star formation in distant galaxies.
“Just like their optical namesakes, gravitational lenses can magnify as well as distort distant galaxies,” they said.
“This allows us to observe the finer details of galaxies that would usually be too distant to clearly resolve.”
“In the case of SGAS J122651.3+215220, the combination of gravitational lensing and Webb’s unprecedented observational capabilities will allow us to measure where, and how fast, stars are forming and also to gain an insight into the environments which support star formation in lensed galaxies.”
“Amid this spectacular display of gravitational lensing, a menagerie of spiral and elliptical galaxies in all shapes and sizes surround the galaxy cluster.”
“Webb’s sensitive infrared instruments have proven prodigious in picking out distant galaxies from the darkness of space.”
“None of the tiny pinpricks in the patch of sky captured here is a star: each one is a galaxy.”
“The variety of colors of the small, dim galaxies gives us hints at what we are seeing: many of the paler white galaxies will date back to the period of intense star formation known as cosmic noon, some two to three billion years after the Big Bang, while the few small orange and red systems are probably from even earlier in the Universe’s history.”
