After 25 years of development costing nearly $ 10 billion, NASA’s James Webb Space Telescope was finally launched on Christmas Day. Assuming there is no problem and the six-ton ââtelescope is able to fully deploy its instruments over the next 5.5 months, eligible scientists will begin to take turns pointing its 47-foot arrays. over 70 feet on whatever interests them.
Yoichi Tamura, a professor in the Division of Particles and Astrophysical Sciences at Nagoya University in Japan, already knows what he’s going to do with JWST when his turn comes. âI would look for the reddest galaxies to identify the most distant galaxies,â Tamura told The Daily Beast.
Tamura and her Japanese, Dutch and American teammates – who have a reservation for observation time with JWST at some point in the future – plan to point the telescope at a pair of suspected “redshift-13” galaxies. The team outlined the potential galaxies and a strategy to study them in a new article that appeared online last month (although it has yet to be peer reviewed).
In astronomy, a “redshift” is the change in the infrared signature of a distant galaxy that helps us determine its age. As the object moves away from the observer, its light increases in wavelength and therefore decreases in frequency and photon energy, causing this light to become more and more red.
Redshift-13 galaxies are found at the outer limits of the known universe, meaning they were among the first outward galaxies when the universe began to expand after the Big Bang 13.8 billion years ago. No less than 13 billion years old, these galaxies are the old people of the universe and the keepers of potentially deep secrets about the origins of, well, all. Thousands of them could be visible from Earth, with the right technology.
Since astronomy is simply a glimpse of light coming from an object, we are literally looking at that object as it was in the past. A distance of 10 light years means that it took 10 years for this light to travel from point A to point B. So the image we get when we look at a high redshift galaxy is the baby image of the object. A long look at a redshift galaxy-13 is a window into an era, billions of years ago, when the universe was young.
Very young galaxies contain very young stars, potentially showing us how these stars are formed, MichaÅ MichaÅowski, an astronomer at Adam Mickiewicz University in Poland, told The Daily Beast. “This is an important topic because these first stars set the stage for future evolution of galaxies by producing the first batch of heavy elements.”
The reddest and therefore oldest galaxy that astronomers have confirmed so far, GN-z11, has a redshift of 11, making it approximately 13.4 billion years old. âWe hope to go further,â Tamura told The Daily Beast. (GN-z11 has sparked controversy lately, after a team of astronomers observed what they believed to be a gamma-ray burst from the distant galaxy and other teams attempted to drill that conclusion. )
Even with JWST at their disposal, Tamura and her teammates face some tough challenges. The hunt for redshift-13 galaxies is difficult. âEarly galaxies are expected to be weak and rare according to the Standard Model of the Universe,â Tamura explained.
Additionally, other nearby galaxies, stars, or even rockets – âintruders,â astronomers call them – tend to interfere with direct observation. Perhaps this is what happened with the alleged GN-z11 gamma-ray burst.
But the biggest obstacle to observing these objects is hydrogen. Neutral hydrogen atoms can absorb much of the light emitted by a galaxy. They can alter the color of the galaxy and blur its true redshift, complicating an accurate assessment of its age and distance from Earth. A lot of hydrogen can accumulate in the vast distances of space and spoil the observations of distant objects. The hydrogen problem gets worse when you look at a distant galaxy from Earth’s hydrogen-rich atmosphere.
There is a solution, but it is incomplete. Using a sophisticated analytical method called the âLyman’s Fracture Technique,â ââastronomers can work backwards from this hydrogen-modified color spectrum. “We are able to make a rough estimate of its distance,” Aaron Yung, a Tamura teammate at NASA’s Goddard Space Flight Center in Maryland, told The Daily Beast.
The Lyman-break method alone cannot identify the redshift of a galaxy. “The distances estimated with this technique have quite large uncertainties and are subject to contamination from foreground objects,” Yung explained. Once astronomers have identified possible redshift-13 galaxies by applying Lyman’s disruption technique to existing surveys, they must point even better – and preferably space-based – telescopes at the same targets, ideally for several days at a time.
This is where the JWST comes in. It is the first of several new space telescopes being deployed or in development that, due to their larger and more sensitive arrays, have a chance to confirm that these dark, reddish objects are ancient galaxies. Along with the JWST, these new telescopes include NASA’s Nancy Grace Roman Space Telescope, which could be launched in the mid-2020s; as well as the Japanese GREX-PLUS, which is still in a decade or more.
Together, these three new telescopes could help astronomers confirm and study not only redshift-13 galaxies, but also older ones. Tamara and her colleagues believe it might even be possible to detect one of the very first galaxies to form, which astronomers say has a redshift of around 17.
The possibilities are almost too strange to be conceived. A redshift-17 galaxy “should be very different from what we see in the neighboring universe,” Tamura said. “It would contain very young star clusters, including even the first generation of stars.”
These newborn stars could be huge – 10 times as massive as the sun – and extremely hot and bright. They can also be short lived and likely to explode. In an image of a redshift-17 galaxy, “shock waves from supernovae would travel through the entire galaxy, making the galaxy very violent,” Tamura explained.
MichaÅowski said he was skeptical, even if such objects exist. âRedshift 17 is only 230 million years after the Big Bang,â he said. “It’s so short that a question remains if there was a galaxy this early at all.”
There is only one way to be sure. Examine the potentially redshift-13 galaxies, then continue to scan deeper and deeper into the far reaches of the universe, looking for ever older and redder galaxies. It all starts with the safe deployment of the James Webb Space Telescope.
Good news on this side. Earlier this week, the gargantuan telescope successfully deployed its tennis court-sized sunshade. On Saturday, it will complete unfolding the second of its two primary mirrors, which means it will finally have finished deploying its larger parts and will be ready to start testing its instruments. The wait has been immense, but it will be worth it if we manage to uncover some of the universe’s greatest secrets.