Astronomers have pushed the NASA/ESA Hubble Space Telescope to its very limits with some amazing results. They have now measured the most remote galaxy ever seen in the universe, crushing the cosmic distance record.
The galaxy known as GN-z11 existed just 400 million years after the Big Bang. It is the first time an object this far out has been measured from its spectrum; this makes the measurement extremely reliable.
GN-z11 lies 13.4 billion light-years from earth, and is located in the direction of the constellation Ursa Major. Researchers believe the newly measured galaxy will provide valuable insights into the first generation of galaxies. The results will be published in the Astrophysical Journal.
The international team of astronomers that measured the distance to this new galaxy found that even though it is extremely faint, the galaxy is unusually bright when you consider the distance it is from earth.
Previous estimates made by astronomers were made by analyzing GN-z11 color in images taken from both Hubble and the NASA Spitzer Space Telescope. However, by using Hubble’s Wide Field Camera 3 (WFC3) the team was able to precisely measure the distance to GN-z11 spectroscopically by splitting the light into its component colors.
Gabriel Brammer from the Space Telescope Science Institute, who is also the second author of the study, explains:
“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.”
How they did it
When determining large distances astronomers measure the redshift of the observed object. Every distant object within our universe appears to be retreating away from us; as a result its light is stretched to longer, redder wavelengths — this phenomenon is a result of the expansion of the universe.
It was thought that the upcoming NASA/ESA/CSA James Webb Space Telescope (JWST) would be the only way to measure galaxies at this type of distance.
Pascal Oesch of Yale University and lead author of the paper, said in a statement:
“We’ve taken a major step back in time, beyond what we’d ever expected to be able to do with Hubble. 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.”
EGSY8p7 was the most distant measured galaxy with a redshift of 8.68. However the team has confirmed that GN-z11’s has a redshift of 11.1, this then corresponds to 400 million years after the Big Bang.
Co-author Rychard Bouwens, from the University of Leiden, explains in the statement:
“The previous record-holder was seen in the middle of the epoch when starlight from primordial galaxies was beginning to heat and lift a fog of cold, hydrogen gas.
“This transitional period is known as the reionisation era. GN-z11 is observed 150 million years earlier, near the very beginning of this transition in the evolution of the universe.”
More questions than answers
According to the esa page, in the observations taken by Hubble and Spitzer it was revealed that the infant galaxy is 25 times smaller than the Milky Way, and has just one percent of our galaxy’s mass in stars. But, the number of stars in GN-z11 is growing fast; the galaxy is creating stars at a rate about 20 times greater than the Milky Way does today.
It is this high rate of star creation that makes the distant galaxy bright enough for Hubble to see and to perform detailed observations. However, this discovery has also raised many new questions; the existence of such a bright and large galaxy is not predicted by theory. Garth Illingworth of the University of California explains:
“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.”
Marijn Franx, a member of the team from the University of Leiden highlighted the need for more study, saying:
“The discovery of GN-z11 was a great surprise to us, as our earlier work had suggested that such bright galaxies should not exist so early in the universe.”
One of Franx colleagues, Ivo Labbe, added:
“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?”