Amazing imagery allows us to find small faint images of different objects that sometimes get smeared out by an effect called gravitational lensing. As weird as it may seem, light is just a fast-moving particle, and its path can be bent by the gravitational pull of any object that light shines past.

Large objects, like massive galaxies, can even act as a funhouse mirror, allowing us to see objects around corners, but twisted and distorted. The thing is, as twisted and distorted as those objects may appear, we aren’t necessarily able to see them any other way. The gravity is actually able to redirect more light in our direction making distant objects also appear brighter. And the objects we’re able to see are some of the earliest galaxies in the universe.

One of the things we don’t acknowledge nearly often enough is that light lets us look back in time. When we look at the sun, we see the light that was released eight minutes ago. When we look at galaxies like the nearby Andromeda we’re looking at light that has been traveling for millions of years, showing us what was instead of what is. As we look at the light that has been traveling from more and more distant galaxies, we are actually seeing what the galaxies looked like at earlier and earlier times in our universe. Through the light-focusing power of gravitational lenses, we’re able to see systems in which the first stars are forming.

Gravitational lenses can also do some pretty weird things. Sometimes, light from the same distant object will get bent toward us along two different paths, and if something flickers or flashes in that distant object — something like a supernova — we’ll see the light arriving at two different times. This effect, and other ways we can measure the distance the light travels, actually let us start to measure the expansion of the universe.

Basically, gravitationally lensed distant galaxies are weird and beautiful and are able to help us understand our universe in a myriad of ways.

And finding them requires amazing data — the kind of data the DESI Legacy Imaging Surveys contain. This single survey has doubled the number of known lenses. The science team is still at the stage of identifying them and working on the science, but like finding a perfectly preserved shipwreck with a bunch of locked chests on the seafloor, we know we have found something, we know it will be amazing, and now we’re just waiting for the details to be unlocked.

More Information

LBNL press release

NOIRLab press release

“Discovering New Strong Gravitational Lenses in the DESI Legacy Imaging Surveys,” X. Huang et al., to be published in The Astrophysical Journal (preprint on arxiv.org)