Washington | Astronomers have shattered the cosmic distance record by discovering the farthest galaxy ever about 13.4 billion light-years away, from a time when the universe was just 400 million years old.
GN-z11 is located in the direction of the constellation of Ursa Major, said an international team of astronomers who pushed NASA’s Hubble Space Telescope to its limits. 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 per cent of its current age, said principal investigator Pascal Oesch of Yale University.
The new Hubble observations take astronomers into a realm that was once thought to be only reachable with NASA’s upcoming James Webb Space Telescope. This measurement provides strong evidence that some unusual and unexpectedly bright galaxies found earlier in Hubble images are really at extraordinary distances. Previously, the team had estimated GN-z11′s distance by determining its colour through imaging with Hubble and NASA’s Spitzer Space Telescope.
Now, for the first time for a galaxy at such an extreme distance, 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. Astronomers measure large distances by determining the redshift of a galaxy.
This phenomenon is a result of the expansion of the universe; every distant object in the universe appears to be receding from us because its light is stretched to longer, redder wavelengths as it travels through expanding space to reach our telescopes. The greater the redshift, the farther the galaxy. 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 the Space Telescope Science Institute (STScI). Before astronomers determined the distance for GN-z11, the most distant galaxy measured spectroscopically had a redshift of 8.68 (13.2 billion years in the past). Now, the team has confirmed GN-z11 to be at a redshift of 11.1, nearly 200 million years closer to the Big Bang.
This is an extraordinary accomplishment for Hubble. It managed to beat all the previous distance records held for years by much larger ground-based telescopes, said Pieter van Dokkum of Yale University. This new record will likely stand until the launch of the James Webb Space Telescope, said van Dokkum.
The combination of Hubble’s and Spitzer’s imaging shows that GN-z11 is 25 times smaller than the Milky Way and has just one per cent of our galaxy’s mass in stars. However, GN-z11 is growing fast, forming stars at a rate about 20 times greater than our galaxy does today.
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