Long ago there was a galaxy far, far away, and scientists have just found it

It is at least 13 billion years old, and a team of scientists from UC Davis has just detected it, confirming that it is the faintest early-universe galaxy yet. Through the use of gravitational lensing and a special attachment to the 10-meter telescope at the W.M. Keck Observatory, located on the summit of Mauna Kea, Hawaii, the team was able to spot the incredibly faint object.

Einstein predicted gravitational lensing. According to UC Davis, this is a phenomenon caused by gravity bending the path of light, therefore magnifying a distant galaxy through the “lens” created by the gravity of another object that exists between the galaxy and the viewer. In this case it was the galaxy cluster known as MACS2129.0741 that caused the gravitational lensing. The new galaxy was located behind this massive cluster, which is large enough to create three different images of the new galaxy. Astronomers knew the three images were the same galaxy due to the showing of similar spectra.

Lead author of the paper Kuang-Han Huang, a UC Davis postdoctoral researcher, the galaxy would not have been visible if its light had not been magnified by the gravitational lens. Huang said that the discovery shows how gravitational lensing can help us understand the faint galaxies that formed during the reionization epoch. This was the period during which stars first appeared, as hydrogen gas between galaxies transitioned to being mostly ionized from being mostly neutral.

Marc Kassis, Keck Observatory staff astronomer, said “This galaxy is exciting because the team infers a very low stellar mass, or only 1 percent of 1 percent of the Milky Way galaxy.” He says, “It’s a very, very small galaxy and at such a great distance, it’s a clue in answering one of the fundamental questions astronomy is trying to understand: What is causing the hydrogen gas at the very beginning of the universe to go from neutral to ionized about 13 billion years ago? That’s when stars turned on and matter became more complex.”

Visualizing what no human has ever seen is only possible due to the Keck Observatories powerful telescopes paired with the gravitational force of massive galaxy clusters. The newly discovered galaxy was original seen by the Hubble Space Telescope as well as the Keck Observatory. However, the special instrument on the 10-meter Keck II telescope was used to confirm that the three visible images were the same object.

Findings were published May 19 in Astrophysical Journal Letters.