Astronomers with early data from the James Webb Space Telescope (JWST) are searching for galaxies that existed only a few hundred million years after the Big Bang.
Astrophysicist Rohan Naidu at the Harvard-Smithsonian Center for Astrophysics, whose colleagues are particularly good at spotting these cosmic relics. Naidu and his collaborators published a paper that caused a sensation on the Internet and created a real buzz on social media . Using data from the “telescope,” the researchers announced that they had discovered a candidate for the most distant galaxy ever discovered, called GLASS-z13. Then, even less than a week later, a number of groups discovered more distant candidate galaxies .
Well, we have another candidate.
In a preprint paper published Aug. 5 but not yet peer-reviewed, Naidu and colleagues detail another distant galaxy candidate, from an early release science program at JWST, Called CEERS-1749. It’s an extremely bright galaxy that, if confirmed, would exist just 220 million years after the Big Bang — and it could rewrite our understanding of the universe.
But there is a huge catch.
CEERS-1749 may be one of the most distant galaxies we have ever seen. Or it could be lurking closer to home. Essentially, the data appear to indicate two possible locations for the Milky Way — and without more observations, we won’t know which one is correct. That earned it the designation “Schrödinger’s galaxy candidate” in a paper submitted to the preprint repository arXiv on Aug. 4.
So, a galaxy like Schrödinger (we use this name because it is more 1749 more interesting) how could it be in two different places? It’s all about redshift .
To determine the distance of a galaxy, astronomers study the wavelength of light. Specifically, they were interested in a light phenomenon known as redshift. In short, light waves leaving distant galaxies are stretched over time, moving the waves down the electromagnetic spectrum and making them more, um… redder. Therefore, ultraviolet light that leaves a galaxy like Schrödinger does not reach Earth the same way ultraviolet light does. Instead, it redshifts into the infrared, which is great for us because that’s the kind of light the JWST is searching for.
JWST has a variety of filters to observe different wavelengths of infrared light. When examining galaxies like Schrödinger, you can browse wavelengths like a photo album. On the first few pages – less red wavelengths – you can’t see anything. Then, when you turn around and the wavelengths get redder, the ghosts of galaxies appear. At the most redshifted wavelengths, on the back of the album, the galaxy is a well-defined object.
Redshift is represented by the parameter z and higher z value means further objects. One of the confirmed most distant galaxies discovered to date, GN-z11, has z value is 11.09. In the case of Schrödinger, the team says its z value may be around 17. This means that this light came from about 13.6 billion years ago.
This also means we may need to reconsider our models of how our galaxies evolved in the early universe – galaxies from a long time ago shouldn’t be this bright, at least according to the models we currently use to explain our universe.
But maybe we don’t need to break physics just yet.
The team believes that there is sufficient environmental evidence that Schrödinger’s z value may be around 5, which means that its light is approximately 12.5 billion years old. Other galaxies in the region around Schrödinger are all around this distance. It’s even possible that Schrödinger is a satellite galaxy of one of its larger neighbors.
But wait, there’s more! Another group of researchers also studied the exact same galaxy from earlier published data, posting their own results to arXiv on the same day. Astrophysicist Jorge Zavala of ALMA Japan and his team added data from Earth telescopes in the French Alps and Hawaii to the JWST data.
They concluded that Schrödinger may have been an imposter masquerading as a high-redshift galaxy . It’s actually a closer, dusty galaxy that’s rapidly forming stars.
Take-home message? The work of this confusing galaxy candidate is incomplete. JWST has been able to study the intensity of the light emitted by Schrödinger, but we need more measurements. In particular, spectroscopy will allow astrophysicists to examine its redshift more accurately. The only hurdle now is time—get enough time on telescopes around the world to study Schrödinger and solve the puzzle.
