Using a quasar as a beacon, scientists found a large protocluster in the young universe; This was the beginning of a giant galaxy cluster that would become the largest known galaxy cluster in the modern universe.

Quasars are the active nuclei of galaxies, that is, supermassive black holes that absorb large amounts of matter. It is believed that such massive objects in the young universe must inevitably be surrounded by a large dark matter halo. The gravitational force of such fields is enormous. So you can look for future galaxy clusters next to bright quasars. This is exactly what the authors of the new work did.

The object of the observations of the group of scientists is the quasar J0910-0414, discovered in 2019 as part of the search for quasars of the reionization period. The redshift of this quasar is 6.64, at which time approximately 826 million years have passed since the Big Bang.

According to scientists, this is one of the largest quasars of that period, with a supermassive black hole mass of approximately 3.59 billion solar masses. For comparison: The mass of the supermassive black hole at the center of the Milky Way is 4.297 million solar masses.

It is important that in the event of such a redshift the quasar comes into the field of view of methods for searching for regions with higher density of matter. Therefore, scientists were able to examine its environment by conducting research at different wavelengths using the Keck Observatory, Subaru Telescope, Magellan Telescopes and ALMA radio telescopes. Astronomers found many “neighbors” in the quasar.

“This protocluster is huge. Compare its size in the sky to other protoclusters that span only a few arcminutes. That’s tens of arcminutes,” commented Feige Wang from the University of Arizona (USA), lead author of the study. An angular minute is one sixtieth of a degree on the celestial sphere.

The study’s authors found three galaxies in the immediate vicinity of the quasar, one of which, along with the quasar, is a satellite of the galaxy. They fit the snapshot of ALMA observations, indicating an extraordinary concentration of matter in this area. According to scientists, this is three times more than expected from an “empty” region.

At a distance of tens of megaparsecs (in the image this area is marked with a yellow rectangle, 35 x 74 megaparsecs), astronomers found 12 more spectroscopically confirmed “seals” with a redshift greater than 6.5. This means they must have co-existed with the quasar in the same period of the universe.

The central protocluster region around the quasar is at most about seven times denser than the average protocluster when the universe was already 3.3 billion years old (red subtraction 2).

Overall, according to the authors’ estimates, today this region should be a galaxy cluster three times larger than the Volos Veronica cluster, with a total mass of about 6.9 quadrillion (6.9×10^15) solar masses. The work was made open access on the following date: arXiv and accepted for publication in the journal Astrophysics Journal Letters.

With this study, scientists proved the ability of the protoscope search method to detect quasars in the young universe. Perhaps, as a result of observing the surroundings of other such objects, it will be possible to find larger protoscopes and understand their impact on the evolution of individual galaxies.

The existence of such a large cluster at such a relatively early period and the abnormally high density of matter in this part of the universe raises two questions at once. First: How could such advanced galaxy clusters have formed so early, since this is inconsistent with the standard cosmological model, which suggests that the formation of the large structures of the universe took an enormous amount of time? Second: Doesn’t the existence of such a matter-rich part of the universe indicate that it is not isotropic, that is, has a kind of isolated “center” where there is more matter and dark matter than elsewhere?