A team of astronomers has discovered an exceptionally luminous galaxy, believed to be the farthest galaxy ever measured. The galaxy, estimated to be more than 13 billion light-years from Earth, has opened a window for astronomers to look at an early cosmic environment when the universe was only 5 percent of its present age.
Dubbed the “EGS-zs8-1,” the galaxy was discovered using the W.M. Keck Observatory’s 10-meter telescope in Hawaii. It was originally identified after NASA’s Hubble and Spitzer space telescopes captured its distinct colors. In a study, published in the journal Astrophysical Journal Letters on Tuesday, researchers said that EGS-zs8-1, which is still forming stars about 80 times faster than the Milky Way galaxy, is one of the brightest and biggest objects in the early universe.
“It has already built more than 15% of the mass of our own Milky Way today,” Pascal Oesch of the Yale University, and the study’s lead author, said in a statement. “But it had only 670 million years to do so. The universe was still very young then.”
The latest observations found EGS-zs8-1 at a time when the universe was undergoing an important change as the hydrogen between galaxies was transitioning from a neutral state to an ionized state. “It appears that the young stars in the early galaxies like EGS-zs8-1 were the main drivers for this transition, called reionization,” Rychard Bouwens of the Leiden Observatory in the Netherlands, and the study’s co-author, said in the statement.
While data from the Keck Observatory, Hubble and Spitzer confirm that massive galaxies already existed in the early universe, they also show that those galaxies had very different physical properties from what is observed today. According to astronomers, the peculiar colors of early galaxies originate from a rapid formation of massive, young stars, which interacted with the ancient gas in these galaxies.
“One of the most dramatic discoveries from Hubble and Spitzer in recent years is the unexpected number of these very bright galaxies at early times close to when the first galaxies formed,” Garth Illingworth, professor of astronomy and astrophysics at the University of California, Santa Cruz, and the study's co-author, said in a statement. “We still don't fully understand what they are and how they relate to the very numerous fainter galaxies.”