Astronomers Saw Some of the Oldest, Brightest Light From the Early Universe

It wasn’t until 800 million years after The Big Bang that the universe’s first light sources emerged. Those ancient, brilliant, energy-dense objects are unfathomably old, and catching sight of one of them is very rare indeed. But thanks to a stunning stellar coincidence, scientists presenting at the 233rd meeting of the American Astronomical Society this week say they have glimpsed one — and it’s the brightest we’ve ever seen.

A 12.8 billion-year-old quasar — a galaxy with a supermassive black hole in its center that expels high-energy particles — recently appeared to astronomers as a galaxy 6 billion light years away serendipitously aligned with it. This coincidence allowed the quasar’s light to pass through the gravitational distortions of a closer galaxy and into the telescopes of astronomers on Earth.

The Hubble Space Telescope snapped some images of the quasar, which was given the unceremonious moniker J043947.08+163415.7 despite being 700 million times the size of the sun and 600 trillion times as bright. The bending and magnifying phenomenon caused by the galaxy — called gravitational lensing — is what allowed the astronomers to observe the quasar, determining it’s the brightest one humans have ever observed from the very early universe.

The international team behind the discovery, led by University of Arizona Professor of Astronomy Xiaohui Fan, Ph.D., presented its findings at AAS in Seattle, Washington on Wednesday. Fan says that he and his collaborators knew from the beginning that they were on to something big, but they didn’t initially recognize just how unique this discovery really was.

“As soon as we were able to measure the distance, we knew immediately that this is a special object in term of its brightness,” he tells Inverse, “but it took us a bit longer to figure out that it was gravitationally lensed.”

Fan and his collaborators observed the quasar named J043947.08+163415.7 because a galaxy in the foreground bent and magnified the light from the distant object. This image, taken by the Hubble Space Telescope, shows how the gravitational lensing effect made the quasar appear split into three.
Fan and his collaborators observed the quasar named J043947.08+163415.7 because a galaxy in the foreground bent and magnified the light from the distant object. This image, taken by the Hubble Space Telescope, shows how the gravitational lensing effect made the quasar appear split into three.

If it hadn’t been for the lensing effect, which both magnified the quasar’s light by a factor of 50 and redirected it toward Earth, astronomers would have missed the quasar altogether. Even to a high-resolution telescope like the Hubble Space Telescope, the light from the quasar would have appeared extremely dim after traveling 12.8 billion light years. Even as the lensing effect made the quasar appear brighter, a sighting like this one needs ample eyes on it to confirm what’s going on. And that it did!

In addition to Hubble, an international network of telescopes collaborated to confirm this finding, including the Gemini Observatory, the James Clerk Maxwell Telescope, the United Kingdom Infra-Red Telescope (UKIRT), the W.M. Keck Observatory, and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1).

“We didn’t expect we could see an object this bright this early in the universe. And the key reason is the lensing effect that boosted the quasar brightness,” says Fan. “This is the first such lensed object discovered in the early universe, even though theory has predicted that it should exist for about 20 years.”

As the light from the quasar passed by a nearer galaxy, the gravity created by the galaxy distorted the light from the quasar, magnifying it and redirecting it toward Earth.
As the light from the quasar passed by a nearer galaxy, the gravity created by the galaxy distorted the light from the quasar, magnifying it and redirecting it toward Earth.

“So the discovery of this object is actually a very nice confirmation of our theory,” he adds.

The team determined the quasar’s age and distance, Fan explains, by measuring the redshift of the wavelength of emissions from hot gas in the quasar. After identifying the signature of gases emitted by the quasar — which included hydrogen and ionized carbon and magnesium — the team was able to measure how much their expected emissions had been shifted by their journey through space. This analysis told the tale of a supermassive black hole 700 million times the size of the sun — and as bright as 600 trillion suns.

The research currently appears as a preprint paper on arXiv, but it will be published in an upcoming issue of the Astrophysical Journal Letters.

The team’s next steps will paint a fuller picture of the quasar and its surroundings.

We are doing a lot of further observations, including a better spectrum that could have high sensitivity to probe the intergalactic gas, and an image that is even sharper than Hubble (using the Atacama Large Millimeter Array) that will study the environment of the supermassive black hole that is powering this quasar,” says Fan.

Media via Fan et al, NASA, ESA, Xiaohui Fan (University of Arizona)