The study of several dozen galaxies within a radius of several billion light years from our own has allowed us to open several black holes that exceed our expectations many times over how large they can grow. The latter research not only helps us better understand the evolution of these mysterious astrophysical objects, but also opens up new interesting questions for us. For example, how do black holes become so incredibly massive?
Black holes, which are the result of a stellar collapse, need no introduction. We have heard that they cause disturbances in space-time , observed their "eructations" and even, perhaps for the first time in history, we will be able to see one of them with our own eyes this year. Scientists are very interested in black holes, and this is understandable reason.
"What are galaxies? These are "bricks" that unite in the general picture of the universe. And to understand how they form and evolve, we first need to understand how black holes work, "says physicist Julia Hlavacek-Larrondo of the University of Montreal (Canada).
Not that black holes themselves simplify this work – it is very difficult to understand what is impossible (as it seems to us) to see directly. Therefore, astrophysicists are looking for other clues that would allow one to dig deeper. One of the directions is to search for a connection between the masses of black holes and galaxies in which they are located. If we had a simple method that allows us to compare the size of galaxies with black holes in their centers, then, in the opinion of scientists, this would save us a lot of time and effort in researching both the first and second.
Therefore, Hlavacek-Larrondo, having joined forces with other scientists from Canada, Spain and Great Britain, conducted a study of 72 galaxies located within a radius of 3.5 billion light years from us, hoping to arrive at some general formula that could simplify the determination of mass black holes in the galactic centers. The scientists shared their observations in the Monthly Notices of the Royal Astronomical Society.
To assess the size of the black holes themselves, a team of researchers conducted an analysis of the spectrum of X-ray radiation escaping from the vortex flows of a hot gas of accretion disks of black holes, and then compared the figures with the overall brightness level of the surrounding galaxy.
According to a rather popular hypothesis, the larger the galaxy itself, the more the black hole itself can be in its center – but in practice everything turned out to be not so simple as expected.
"We found that black holes can be much larger than the estimated statutory sizes," commented lead author Mar Mezqua of the Institute of Space Sciences in Spain.
Instead of the expected correlation in mass and size with their galaxies, a number of black holes showed much faster growth and mass gain compared to the rest of the surrounding space. It turned out that about 40 percent of the investigated black holes have a mass that is 10 and more billion times greater than the mass of the Sun. Here the truth should be clarified that no records of the mass were recorded, and the championship still belongs to the black hole of the galaxy NGC 4889, whose mass is equivalent to 21 billion solar masses. In addition, it is suspected that the galaxy S5 0014 + 81, located 12.1 billion light years from us, contains a real monster with a mass of about 40 billion Suns. But nevertheless, such a large number of supermassive black holes made scientists think about how they become such.
The researchers have two assumptions about this: either these black holes initially appeared very large, and then literally attracted most of the galaxy's matter around them, or there are serious gaps in our knowledge of how galaxies produce black holes.
"Are they so big, because they immediately appeared, or were they helped by ideal conditions that allowed them to grow very rapidly for several billion years? At the moment, we can not answer this question, "Mezqua said.
However, the answer to this question may be contained in another study published in the largest online library of scientific papers arXiv.org and pending verification. In its course, scientists studied more than 30,000 galaxies located within a radius of 12.2 billion light-years, and found that the ratio of the growth rate of black holes and the growth rate of stars accelerated with the growth of the galaxies in which the investigated objects were located. In other words, for galaxies with a large number of stars, black holes are always "gluttonous".
A more general conclusion from these studies is that there really is a connection between star formation and black holes, and it is very confusing. Of course, it will take more than a dozen studies in order to better understand it. But one thing becomes clear right now – without these giants our Universe would look quite different.