Leap back in time: NASA spots farthest galaxy, breaks cosmic distance record
Even though GN-z11 ‒ or, as scientists dubbed it, the “infant galaxy” ‒ is extremely faint, it is unusually bright for its remoteness from Earth.
Never before has the NASA/ESA Hubble Space Telescope managed to reach as far as 400 million years after the Big Bang and precisely measure the distance to GN-z11. NASA says it has now broken “the cosmic distance record.”
“We’ve taken a major step back in time, beyond what we’d ever expected to be able to do with Hubble,” said Pascal Oesch of Yale University, the lead author of the paper about the find. “We managed to look back in time to measure the distance to a galaxy when the Universe was only three percent of its current age.”
To reach that far, Hubble measured distance of GN-z11 from its spectrum by splitting the light into its component colors.
In order to determine large distances, astronomers measured what is known as “redshift,” which means longer and “redder” wavelengths from when light of distant objects stretches as they recede from us. Hence, redshift appears as a result of the expansion of the Universe.
“Our spectroscopic observations reveal the galaxy to be even further away than we had originally thought, right at the distance limit of what Hubble can observe,” Gabriel Brammer of the Space Telescope Science Institute and second author of the study said.
Previously, to estimate GN-z11’s distance astronomers had to analyze its color in images taken with both Hubble and the NASA Spitzer Space Telescope. Now the team has used Hubble’s Wide Field Camera 3 (WFC3).
GN-z11’s distance has a redshift of 11.1, which corresponds to 400 million years after the Big Bang, a distance that was believed only to be reachable with the next generation NASA/ESA/CSA James Webb Space Telescope (JWST). Until now, the most distant measured galaxy was EGSY8p7 with a redshift of 8.68, located 13.2 billion years in the past.
“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,” explains Garth Illingworth of the University of California in Santa Cruz.
As NASA’s findings show, GN-z11 is 25 times smaller than the Milky Way, but it is forming stars at a rate about 20 times greater than our galaxy.