Most Distant Gravitational Lensing Galaxy Ever Found
The most distant gravitationally-lensing galaxy ever discovered has been announced by astronomers and it is showing us a galaxy almost 11 billion light-years away.
This phenomenon occurs when a gravitational source in space bends the light of a more distant object, magnifying and distorting it for our eyes here on earth.
You might ask how massless photons of light can be effected in this way. As usual, we have Einstein and his General Theory of Relativity to thank.
A key and revolutionary concept of his was that gravitation could be thought of as a manifestation of the curvature of space-time. More gravity = more curvature. There’s a cool feedback between mass/gravity, space-time, and motion. I forget who first put it this way, maybe Einy himself. Mass tells space-time how to form and space-time tells mass how to move.
(I just googled it, physicist John Wheeler appears to have said this)
Photons of light then are just following the shape of space-time it finds itself in whether it’s a straight line, slighly bent, or circuitous as hell. Not that the photon knows any better. Since it’s traveling by definition at the speed of light, time doesn’t even exist for it. Whether it travels a pico-meter or peta-parsecs it doesn’t matter.
Back to the lensing…
Observations of galaxy data at the Keck Observatory in Hawaii showed a blob of light which indicated a star forming region. Since the 9.6 billion light-year distant galaxy being observed shouldn’t have had any of that, a red flag was raised.Cross-checking with higher resolution Hubble images confirmed something unusual indeed. That blob was a star birthing spiral galaxy, 10.7 billion light years away.
This source lensing galaxy at 9.6 billion years away is 200 million light years more distant than any other found before. It’s an extremely rare event for two reasons. The source galaxy is very big at 180 billion solar masses. Ok, this may not seem big compared to the closer, more modern and hip galaxies you’ve heard of but galaxies from this early era of the universe are almost never that big.
Secondly, for such a distant galaxy to line up so precisely with another galaxy is exceedingly lucky. Lead researcher Kim-Vy Tran of Texas A&M University compares it to a magnifying glass. If you hold it at arm’s length it’s not hard to magnify something. If, however, you move the glass to the far side of the room, it becomes considerably more difficult to line it up just right so you can see anything clearly.
This discovery and hopefully more in the future could potentially show us how small, young-universe galaxies evolved into the huge dark-matter dominated behemoths found near us today.