The space telescope James Webb detected a strange galaxy that existed in the early Universe and its growth differed from most galaxies it appears to have happened from the inside out, with stars forming more quickly at the edges than inside their dense core.
The galaxy, called JADES-GS+53.18343−27.79097, existed just 700 million years after the Big Bang and is about 100 times smaller than our galaxy. Theoretical models predicted that such inside-out galaxies should be common throughout the early Universe, but scientists previously lacked the ability to penetrate the dust and gas surrounding them.
With publication in the magazine “Nature Astronomy” the research group presents the results of observations with James Webb. “One of the many reasons Webb is so transformative for us as astronomers is that we are now able to observe what has previously been predicted through cosmological models. It’s like being able to check your work,” says William Becker, a postgraduate student at the University of Cambridge and member of the research team.
Galaxies grow in two main ways: by capturing enough gas to form new stars or through mergers with smaller galaxies. But it is still unclear whether these are the only mechanisms or whether there may have been other cosmic processes in earlier phases of the Universe.
“The question of how galaxies evolve over cosmic time is an important one in astrophysics. We had lots of great data from a few million years ago and from distant, ancient galaxies, but now with James Webb, we can get observational data from billions of years back in time, investigating the first billion years of cosmic history, the which opens up all sorts of new questions,” he says. Sandro Taxhella, professor of astrophysics at the University of Cambridge, one of the heads of the research team.
To investigate this question, researchers analyzed data from ancient galaxies collected during James Webb’s JWST Advanced Deep Extragalactic Survey (JADES). Light travels at a constant speed through the void of Space, so the deeper the JWST looks into the Universe, the further away the light it intercepts and the further back in time it essentially allows astronomers to see.
The light
Examination of these observations revealed the new galaxy to astronomers. By analyzing the light coming from the stars inside, researchers were able to estimate its age.
They found that the galaxy has a very dense core and is surrounded by a disk of gas and dust whose stars are forming rapidly – causing the galaxy to double in size once every 10 million years. Once these stars take shape, they slowly migrate toward the core and make the galaxy spin faster, like a skater bringing his arms closer to his body, say the researchers, who report that they will now look for other similar galaxies.
“Of course, this is just one galaxy, so we need to know what the other galaxies were doing at the time. Were all galaxies like him? We are now analyzing similar data from other galaxies. By observing different galaxies over cosmic time, we may be able to reconstruct the growth cycle and show how galaxies grow to their final size today,” says Taxchela.
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