The record for most distant ever seen may have been broken by two galaxies. The light from these galaxies has taken over 13 billion years to reach us, and they were just a little over 300 million years after the Big bang!
Paper 1 and Paper 2 can be found here.
The surveys used to find the galaxies were very deep, meaning they see very faint objects. The key here is that they all detect the light from the IR. First, very distant galaxies should be forming stars at a rapid rate as their central black holes feed on material falling into them. The processes emit a lot of light.
The Universe is expanding. As space grows, objects are swept away from us. The wavelength of the light they emit is similar to the sound. The object's light is redshifted when it's more distant.
The wavelength of distant galaxies should be stretched ten times. IR telescopes are used to look for ultra violet light emitted by a distant galaxy.
The gas in the early Universe was hydrogen. The electron in a hydrogen atom gets blown if it absorbs a UV photon at a critical wavelength. The shorter wavelength light will get absorbed, but the longer wavelength light can get past. When we look at nearby galaxies that emit a lot of UV light, they don't emit light with shorter wavelength. There is a cut off there.
Astronomers can see the redshift of a distant galaxy by looking at it using a bunch of different filters that select for specific wavelengths and arranging them from blue to red. At a certain redshift, the bluest filters don't see any light, but suddenly the galaxy appears in a redder filter. The wavelength of the filter tells us how much redshifted the cutoff was. The distance to the galaxy is given by that.
Astronomers used the IR telescopes to measure the colors of thousands of galaxies in the surveys. They found that it had been redshifted into theIR, indicating immense distance.
They call them HD1 and HD2. The first has a redshift factor of 13 and the second 12.3. It took the light of the galaxies to reach us about 13 and a half billion years after the Big bang.
Whoa.
The farthest galaxy we have ever seen has a redshift of about 11 and was 400 million years after the creation of the Universe. HD1 and HD2 are not close to each other.
The two galaxies are emitting a lot more ultraviolet light than expected. There could be two reasons for this. They are forming stars between 5 and 24 times what models indicated. If this is true, they are making a lot more massive stars than expected. It is thought that when hydrogen and helium were abundant, stars could grow to be much larger than they are today. We haven't seen these first generation stars yet, but all the extra UV light pouring out of these galaxies means it could be coming from them.
The second reason is that the central black holes in the galaxies could be quasars, where they are feeding on material. The black holes would have to be at least one hundred million times the mass of the Sun. We see bigger ones than that, but they are the same as when they were young. It takes a long time to build a huge black hole. It's possible to get them that big by that time if they were born very large.
The evidence is pretty compelling, but it isn't proof. It will have to wait for a telescope like the James Webb Space Telescope to confirm, since it has a big enough mirror to see such faint galaxies. It is possible to prove or refute the huge redshift.
It could take a year or two to determine. The Nancy Roman Space Telescope is planned for launch in a few years and may find more such galaxies.
It is interesting that these are the farthest ever seen, but they may not hold that record for long.
The shape and structure of the Universe is usually not a problem, but we are talking about objects so close to the observable edge of the Universe that they become important. A small change in density can translate into a big change in distance. I use the same numbers as the published papers to get the distances, but you might see different numbers in other articles. Don't worry about the numbers, but instead look at the bigger picture, because we're seeing farther back in the Universe than ever before.
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