“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,” observed Pascal Oesch at the University of Geneva and head of the Galaxy Build-Up at Cosmic Dawn team about the discovery of a 13.4 billion-years -old galaxy. It’s mind-boggling by comparison to think that Earth is only 4.5 billion years old.
Complex Life in a Galaxy Near the Dawn of Time?
The discovery underscores Edwin Hubble’s observation that the history of astronomy is a history of receding horizons.
When asked about the possibility of complex life in a galaxy near the dawn of time, astrophysicist Brian Thomas at Washburn University replied to an email from The Daily Galaxy: “First, my guess is that rocky planets, which might be a requirement for life, aren’t likely in a very young universe without a high abundance of heavy elements (due to not many generations of stars). Not impossible, but more rare than we see today.
“Second,” Thomas continued, “I see that this galaxy appears to have a lot of star formation going on. Bursts of star formation are followed relatively quickly by a lot of supernovae (SNe). Gamma-ray bursts (GRBs) are also likely, and may be more likely there than in the Milky Way since there is an apparent connection between low metallicity galaxies and higher rate of GRBs. Both SNe and GRBs are threatening to life. I’m guessing the stellar density may be relatively high (like in the central part of the Milky Way), which makes it more likely that a planet would be subjected to large amounts of radiation from SNe and GRBs.
“Overall,” Thomas concluded, “I think the odds aren’t great for complex life in this environment.”
Echoing Thomas, astrobiologist Manasvi Lingam at Florida Institute of Technology, an affiliate of the Institute for Theory and Computation at Harvard University, wrote in an email to The Daily Galaxy. “Life, at the minimum, requires habitable conditions, solvent (e.g., water), energy sources, and bioessential elements. Since GN-z11 is so old, the number of habitable planets is likely to be small due to the lower numbers of stars in that epoch.Moreover, the availability of heavier elements necessary for Earth-based biology (such as iron and molybdenum) is questionable because enough supernovae may not have occurred and seeded the planets with these elements.”
“Overall,” Lingam concluded, “I believe that the likelihood of life is rather low in that galaxy at that point in time, especially complex life, which calls for additional requirements (e.g., cellular differentiation). With that said, we should keep an open mind and not dismiss alternative possibilities altogether.”
The results reveal surprising new clues about the nature of the very early universe. “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,” explained investigator Garth Illingworth of the University of California, Santa Cruz.
Previously, the Universe’s most distant galaxy was known as EGS8p7, whose light was redshifted by an extra factor of 8.63 before it reached Earth, from 13.24 billion years ago: when the Universe was just 573 million years old, or only 4% of its current age.
The newest record-holder has had its light redshifted by a whopping factor of 11.1, meaning the light is even older: it was emitted 13.40 billion years ago, when the Universe was only 407 million years old, or closer in time to the Big Bang than any other galaxy ever seen before. You have to be extremely not just skilled, but also extremely lucky to see a galaxy this far back in time using the Hubble Space Telescope.
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.
By pushing NASA’s Hubble Space Telescope to its limits, an international team of astronomers has shattered the cosmic distance record by measuring the farthest galaxy ever seen in the universe. This surprisingly bright infant galaxy, named GN-z11, is seen as it was 13.40 billion years in the past, just 4070 million years after the Big Bang. GN-z11 is located in the direction of the constellation of Ursa Major.
This animation shows the location of galaxy GN-z11, which is the farthest galaxy ever seen. The video begins by locating the Big Dipper, then showing the constellation Ursa Major. It then zooms into the GOODS North field of galaxies, and ends with a Hubble image of the young galaxy. GN-z11 is shown as it existed 13.40 billion years in the past, just 4070 million years after the big bang, when the universe was only three percent of its present age.
The discovery team included scientists from Yale University, the Space Telescope Science Institute (STScI), and the University of California.
Astronomers continue closing in on the first galaxies that formed in the universe. 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 color 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 colors.
“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.
Ancestor of the Milky Way Disovered
Astronomers have uncovered another ancient cosmic artifact 11 billion light-years from Earth: the oldest spiral galaxy ever seen. The newly discovered galaxy, known as A1689B11is an ancestor of modern spiral galaxies like our own Milky Way, which are defined by long tentacles of gas, dust and stars that wrap around the galaxy’s central bulge.
“Spiral galaxies are exceptionally rare in the early universe, and this discovery opens the door to investigating how galaxies transition from highly chaotic, turbulent discs to tranquil, thin discs like those of our own Milky Way galaxy,” said Renyue Cen, a senior research astronomer at Princeton University.
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 investigator Pieter van Dokkum of Yale University. “This new record will likely stand until the launch of the James Webb Space Telescope.”
The combination of Hubble’s and Spitzer’s imaging reveals that GN-z11 is 25 times smaller than the Milky Way and has just one percent of our galaxy’s mass in stars. However, the newborn GN-z11 is growing fast, forming stars at a rate about 20 times greater than our galaxy does today. This makes an extremely remote galaxy bright enough for astronomers to find and perform detailed observations with both Hubble and Spitzer.
These findings provide a tantalizing preview of the observations that the James Webb Space Telescope will perform after it is launched into space in 2021.. “Hubble and Spitzer are already reaching into Webb territory,” Oesch said.
“This new discovery shows that the Webb telescope will surely find many such young galaxies reaching back to when the first galaxies were forming,” added Illingworth.
“The discovery of GN-z11 proves that galaxy build-up was well underway at ~400 million years after the Big Bang,” Pascal Oesch told The Daily Galaxy. “We still do not know much about the nature of GN-z11, however. For instance, it is possible that part of its luminosity originates from an AGN. In any case, our discovery indicates that we should find numerous progenitors of GN-z11-like galaxies out to much higher redshifts with JWST in the near future, and we are all eagerly awaiting its launch and science operations.”
Image at top of page: Artist rendering of GN-z11