How to explain the existence of intermediate black holes?

The first candidates for the black hole of the stars was discovered in the early 1970s with the advent of especially X-ray astronomy. But we can say that the first candidates for the title of black hole tout court were discovered in the early 1960s with quasars. In the following years from the end of XXand century, it is becoming more and more likely that black holes featured stars had masses between 5 and 15 solar masses while supermassive black holes in the heart of large galaxies, such as The Milky Waycontained from one million to several billion solar masses.

If the birth of the stars’ black holes is not very mysterious, too collapse the gravity of a star at the end of its life, probably containing initially more than 30 solar masses, the gravity of supermassive black holes is still enigmatic, although several plausible scenarios have been put forward. This implies the existence of black holes with intermediate mass between the two populations that could merge due to the collision of galaxies and also the accumulation of matter coming from streams ofhydrogen falling on galaxies or by sinking stars.

This last hypothesis is not without problems because it is well known that in galaxies the distances between stars are such that they can be considered to form a gas without collision. But today an article was published in The Astrophysical Journal of a team ofastrophysicists and which can be read freely on arXiv allows us to reconsider this scenario in a different light, making it much more interesting and credible.

For about a decade, there have been indications of the existence of intermediate black holes, and what now seems promising to explain at least part of this existence is that in a remarkable fraction of the large galaxies we find clusters of core stars. Those nuclear star cluster (NSC), as we say in English, is at the center of most spiral galaxies and they are closer (by 106 at 108 solar masses in the form of stars in an area of ​​about tenlight years radius) end kuglehobe and open clusters of stars, while containing both old stars, such as the former, and young stars, such as the latter.

Star Meeting Catalysts

NSCs are found mainly in galaxies that are not too massive, such as the Milky Way, and generally in those where the lightest supermassive black holes are observed, if at all. Our Galaxy has NSCs and its central giant black hole contains only about 4 million solar masses.

Observations made in the area by X-rays with telescope spatial Chandra and in the visible with the telescope Hubble highlighted in more than 100 galaxies NSCs containing special black holes in a sample of 29 that emerged from studies of data collected by the two instruments jointly.

They seem to confirm a theory of growth in avalanche the black holes of the stars in these clusters, the density of which allows stars to approach these black holes to the point where they are destroyed by tidal forces, giving rise to the famous Tide disturbances (or TDE), which can be translated into French as “tidal effect events”, already modeled during the 1980s by Jean Pierre Luminet and Brandon Carter.

In an NSC, according to scientists’ calculations, a star hole born in the center will then destroy and swallow the matter from thousands of stars, thus turning into a black hole with an intermediate mass towards the center of the galaxies. The calculations also show that there is a density limit and it also depends on speed to which the stars in the clusters move, from which the star-consuming growth process in earnest begins.

As predicted by the theory, NSCs above the calculated threshold contain several growing black holes, which supports the theory. The process of runaway growth can occur in any sufficiently dense cluster and therefore still today in the universe and not in the beginning of its history. Which is another testable prediction.

A brief presentation of the discovery of the possible origin of intermediate black holes. To get a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles were then to be displayed. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Automatically translate”. Select “French”. © Chandra X-ray Observatory

Interested in what you just read?

Leave a Comment