NASA
The data from the Webb Space Telescope has only gotten into the hands of astronomers in recent weeks, but they’ve been waiting for it for years, and it looks like the analyzes are ready. The result was like a race through time, as new discoveries found objects that formed much closer to the Big Bang that produced our universe. last week, One of these searches A galaxy that existed appeared less than 400 million years after the Big Bang. This week, a new analysis revealed a galaxy that appeared just 233 million years after the emergence of the universe.
This discovery is a happy byproduct of work designed to answer a more general question: How many galaxies should we expect to see at different time points after the Big Bang?
Back in time
As we reported last week, the early universe was opaque to light at any wavelength carrying more energy than is required to ionize hydrogen. This energy is in the ultraviolet part of the spectrum, but the redshift caused by the 13-billion-year expansion of the universe has converted this cutoff point to the infrared part of the spectrum. To find galaxies of this age, we have to look for objects that are not visible at shorter infrared wavelengths (meaning the light was once above the hydrogen cut-off point), but appear at lower energy wavelengths.
The deeper the boundary between visible and invisible in infrared, the stronger the redshift and the farther away the object is. The farther away an object is, the closer the time to the Big Bang.
Studies of these galaxies can tell us something about their individual properties. But identifying a large group of early galaxies can help us determine how quickly they formed and identify any changes in galactic dynamics that occurred at a particular time in the universe’s past. This change over time in the frequency of visible objects is called the ‘luminosity function’, and some work has been done to describe the luminosity function of early galaxies. But the infrared wavelengths of the first galaxies are absorbed by the Earth’s atmosphere, and therefore must be imaged from space. This was one of the design goals of the Webb Telescope.
The new work focused on examining the luminosity function of galaxies that formed soon (in astronomical terms) after the Big Bang. But when creating a catalog of early galaxies, researchers discovered what appears to be the oldest galaxy ever photographed.
Job selection
The researchers used two data sources to reconstruct how galaxies looked at different times. One was produced by analyzing work done with an infrared telescope (ESA’s telescope view) and the Spitzer Space Telescope, both of which image galaxies relatively older when they produced the light that now reaches Earth — about 600 million years or so after the Big Bang. Other embedded data generated by Webb, including the datasets analyzed in the article inform us The area was photographed The first public image release. In each case, the researchers looked for the same thing: things that were present in the longer infrared waves but absent in the shorter ones.
In all, the team identified 55 distant galaxies, 44 of which had not been observed before. Thirty-nine of them come from web data, and this number includes the two ancient galaxies identified last week. The numbers are not particularly accurate for high redshifts, as they are based on only one or two galaxies. But in general, the trend is a gradual decrease in visible objects within a few hundred million years after the Big Bang, without sharp changes or cuts.
But the amazing thing is that there are data for a galaxy with a very large redshift (z = 16.7, for those who understand such things). This puts it at less than 250 million years after the Big Bang. This distance depends in part on the fact that the first wavelength filter at which the object appears is very weak, indicating that it is weak at the wavelengths allowed by the filter. This indicates that the hydrogen-induced light cutoff is close to the edge of the filter strip.
Like the distant galaxies described last week, it also appears to have the equivalent of a billion suns of star-shaped matter. Researchers estimate that it may have started forming stars 120 million years after the Big Bang, and it certainly happened 220 million years ago.
The researchers are quite confident that this new galaxy is a real discovery: “After extensive research, we cannot find any reasonable explanation for this object, other than a new redshift galaxy.” And by adding a second, independent confirmation of previous galactic discoveries, it greatly increases our confidence in these discoveries. All this indicates that the new telescope is living up to its promises, at least with regard to early galaxies.
The big question now is what will appear when they are directed toward regions with higher lenses, which might be able to zoom in on objects to a point where we can visualize the structures within these early galaxies. We may have already done that, but we will have to wait for the descriptions to appear in the arXiv file.
arXiv file. Abstract number: 2207.12356 (About arXiv).
