Peek into the distant past

The measurement to the GN-z11 galaxy not only allows us to look further into space, but further back in time; image source: University of Melbourne
Australian astronomers from Melbourne and Macquarie Universities have contributed to international research that has pushed NASA's Hubble Space Telescope to its limits.

They measured the distance to the farthest galaxy we can see, shattering the cosmic distance record.

This surprisingly bright galaxy, named GN-z11, is located 13.4 billion light-years away in the direction of the constellation of Ursa Major. The galaxy, the furthest ever seen in the Universe, existed just 400 million years after the Big Bang.

For the first time for a galaxy at such extreme distances, the team used Hubble’s Wide Field Camera 3 to precisely measure the distance to GN-z11 spectroscopically by splitting the light into its component colours. Previously, astronomers had estimated GN-z11’s distance by determining its color through imaging with Hubble and NASA’s Spitzer Space Telescopes.

The measurement provides additional strong evidence that some unusually bright galaxies found in earlier Hubble images are among the first galaxies that formed in the universe.

It also reveals surprising new clues about the nature of the first generations of stars formed in the Universe, including that early star formation may have been more efficient than previously thought and that early galaxies grew very rapidly.

This discovery has important consequences for upcoming Australian observations with the Murchison Widefield Array (MWA) radio telescope, which will study the process of cosmic re-ionization.

The light from young stars of galaxies like GN-z11 is expected to ionize the neutral hydrogen gas, making the Universe transparent to radiation.

The MWA will be able to observe the transition of the gas from neutral to ionized, providing complementary evidence to these Hubble observations to understand star formation in the youth of the Universe.

The team’s findings will appear in the March 8, 2016 edition of the Astrophysical Journal.

Story based on a media release from the University of Melbourne