Astronomers examined an ancient galaxy using the James Webb telescope. It turns out that it was not one, but two merging galaxies that were actively forming new stars just 510 million years after the Big Bang.

The further a space object is from us, the fainter it is. Although we can see bright galaxies in the early universe, only 300-500 million years after the Big Bang, technology does not yet allow us to study them in detail. And the details help scientists confirm hypotheses about how the first galaxies managed to accumulate mass and form stars so quickly. Perhaps the answer to this question will help find the Gz9p3 galaxy.

This galaxy was detected several years ago in data from the Hubble Space Telescope. It was just a dot. The James Webb telescope is more powerful, so with its help astronomers managed to study the internal structure of the object. The results of the research were published in the journal Nature Astronomy.

The Gz9p3 galaxy, as the authors of the new paper call it, has a redshift of z=9.3, meaning we see it about 510 million years after the Big Bang. Scientists drew attention to it for its extraordinary brightness.

Later observations confirmed that Gz9p3 was 50% brighter than ordinary galaxies of its time. At most, it turned out to be very powerful: 1.6 billion solar masses. All this makes it the brightest and largest galaxy of its period with z = 9. Even accounting for candidate galaxies, it is one of the most powerful galaxies we know of in the first 750 million years after the Big Bang. .

Its structure and stars are even more interesting. According to the study’s authors, Gz9p3 forms stars with a total mass of about 19 solar masses per year (range, 13 to 24 solar masses). For comparison: the rate of formation of new stars in Andromeda is 0.4 solar masses, and in the Milky Way it is between one and two solar masses. However, astronomers have calculated that by 2023 this rate could be much higher, between four and eight solar masses per year. However, it is equally much less than that of Gz9p3.

The observations also revealed that Gz9p3 is actually two galaxies merging. The age of the youngest stars here is less than 10 million years, and the “old” generation is on average 120 million years old. Considering the age of the universe at that time, it turns out that the formation of these stars began only 300 million years after the Big Bang.

How often are such fusion products found in the young universe? According to the study’s authors, the probability of “catching” such an object is about 20%, so Gz9p3 is nothing unique. However, the total mass of the stars inside is greater than scientists expected. This makes it an excellent candidate for further study.

As the scientists explain, either the galaxy is in a strong dark matter halo, which is rare for that era, or we do not understand something about the formation of stars in the early universe. More precisely, the second one. Therefore, by studying Gz9p3 in more detail, especially its motion and interactions within it, we can learn more about the dark matter halo, star formation, and conditions in interstellar, intragalactic, and intergalactic space at that time.

The Hubble Space Telescope found many candidate galaxies at redshifts eight to 11, corresponding to 600 to 400 million years after the Big Bang. With the help of “Spitzer”, astronomers discovered quite old stars in them, that is, the formation of stars in the universe began quite early.

With the launch of “James Webb”, not only did the list of galaxies known to us at z>10 increase, but it also became possible to examine objects that were slightly closer at z=8 spectroscopically. It turned out that there were many more galaxies than the models predicted at that time. Particularly bright galaxies. And thanks to objects like Gz9p3, astronomers can study the conditions of their formation.