Hubble spots farthest galaxy in the known universe 13.4 billion light years away

Astronomers using the Hubble Space Telescope have spotted a bright galaxy located a record-breaking 13.4 billion light years away, the most distant object ever seen in the known universe. Located in the direction of the constellation Ursa Major, the unexpectedly bright galaxy was formed just 400 million years after the Big Bang gave birth to the universe.

"We've taken a major step back in time, beyond what we'd ever expected to be able to do with Hubble. We see GN-z11 at a time when the universe was only three percent of its current age," explained principal investigator Pascal Oesch of Yale University in a statement.

Scientists had previously estimated the galaxy's distance by analysing its colours in images taken from Hubble and Nasa's Spitzer Space Telescope. For the first time – for such a galaxy located at such an extreme distance – the team used Hubble's Wide Field Camera 3, which was installed during the last astronaut servicing mission in 2009, to pinpoint the distance to GN-z11 spectroscopically by splitting the light emitted from the cosmic object into component colours.

"Our spectroscopic observations reveal the galaxy to be even farther away than we had originally thought, right at the distance limit of what Hubble can observe," said Gabriel Brammer of STScI, second author of the study.

The observation is a major step back in time to when the universe was just 3% of its current age – about 13.8 billion years old – and could provide incredible insight into the formation of the universe.

To discuss distance in the cosmos, astronomers use the term "redshift" to measure how much light has stretched by the expansion of the universe as it travels through space. Higher redshift values assigned to a cosmic object correspond to greater distances. GN-z11 has been assigned a whopping redshift value of 11.1. The previously "most distant" galaxy, known as EGSY8p7 was discovered in August 2015 and given a redshift of 8.68, about 13.2 billion years away.

GN-z11 is 25 times smaller than the Milky Way with just 1% of the mass of the Milky Way's stars. However, it is growing fast, forming stars at a rate that is about 20 times faster than the Milky Way produces today. Its rapid star formation makes the distant galaxy bright enough for scientists to observe, analyze and measure it.

"It's amazing that a galaxy so massive existed only 200 million to 300 million years after the very first stars started to form. It takes really fast growth, producing stars at a huge rate, to have formed a galaxy that is a billion solar masses so soon," said Garth Illingworth of the University of California, Santa Cruz. "This new discovery shows that the Webb telescope will surely find many such young galaxies reaching back to when the first galaxies were forming."

The distant galaxy's discovery was also an unexpected one for astronomers. "The discovery of GN-z11 showed us that our knowledge about the early Universe is still very restricted. How GN-z11 was created remains somewhat of a mystery for now. Probably we are seeing the first generations of stars forming around black holes?" Ivo Labbe, a member of the University of Leiden team said.

The latest observation could be an exciting preview of the next frontier in astronomy and future observations made with the James Webb Space Telescope, Hubble's successor that is specifically designed to look back at objects formed just after the Big Bang. It is expected to be launched into space in 2018.

The team's research will be published in the latest issue of The Astrophysical Journal.