There’s something strange about this image taken by the Hubble Space Telescope. If you look closely, you can see two almost mirror images, two orange galaxies that seem to be connected by a long thread.
Surprisingly, it is not two galaxies at all, but one, called SGAS J143845+145407. There are only two of them, thanks to the way the gravity of a massive object (or things like a group of galaxies) distorts the space through which distant light travels.
Imagine that a heavy weight is placed on a trampoline, where the weight represents the mass of galaxies and the trampoline mat represents space-time. Now roll some balls from one side of the trampoline to the other. Its usual “straight” paths will curve along different paths, not unlike light rays passing through a distorted space.
This gravitational aberration, called gravitational lensing, can be used to magnify the light from background galaxies that are too far away to see in detail, as shown in the graph below.
Thus, such gravitational lensing can be an important tool for understanding the distant universe.
Sometimes this light can warp and distort, as can be seen in a recent deep-field image taken by the James Webb Space Telescope. These strange, wobbly, worm-like objects are lenticular galaxies. When the lensing effect causes four images of a distant object to line up around a central lens block, this is called an Einstein cross.
SGAS J143845+145407 appears in just the right place behind a small cluster of gravitational lensing galaxies, producing two near-perfect images of the galaxy, with the added benefit of appearing larger and more detailed.
The light from SGAS J143845+145407 took about 6.9 billion years to reach us. This is roughly half the life of the current universe. The cluster’s light traveled for about 2.8 billion years.
SGAS J143845+145407 is of scientific interest because it is an infrared luminous galaxy that shines relatively brightly due to high star formation activity. Studying galaxies like this can help scientists understand star formation and how it has changed throughout the history of the universe. For this type of work, gravity lenses can be indispensable.
Using gravitational lensing, researchers have recently been able to reconstruct the distribution of star formation in SGAS J143845+145407 and study the details of the process. They found that the galaxy is largely typical of its kind, that is, information that can help contextualize and characterize other galaxies.
Webb is expected to reveal more details, but Hubble has revolutionized the study of lenticular galaxies. His observations were the first to reveal details within lenticular galaxies, giving scientists a stunning new window into the early universe.
The image was published on Hubble’s website.