A ‘false’ black hole: Instead of swallowing stars, it creates them

the black holesthose confusing cosmic things that make the imaginations of science fiction authors fly and in whose intimate relationship the laws of physics disappear, never cease to amaze: Researchers from the University of Montana’s eXtreme Gravity Institute note that one located in the center of a dwarf galaxy helps ignite it rather than devour and destroy it. The work has just been published in the magazine temperamental nature (https://doi.org/10.1038/s41586-021-04215-6).

These strange entities predicted by Einstein’s theory of relativity and named by physicist John Wheeler, whose gravity is so strong that it distorts the geometry of the universe and even prevents light from escaping, are often described as cosmic monsters that swallow up everything beyond the “event horizon”. But those at the center of the Haines 2-10 dwarf galaxy, about 9 megaparsecs from Earth or about 30 million light-years away, in the southern constellation of Pyxis, are the “seeding” of stars..

Using the Hubble Space Telescope (which has doubled its estimated lifespan), study authors Zachary Schott and Amy Rhimes captured a crystal-clear visual image of the relationship between a black hole and its neighboring star-forming region, a flow of energy. “That stretches through space like an umbilical cord toward a wonderful stellar nursery,” said a NASA statement.. The flow is moving at 1.6 million kilometers per hour and clusters of newborn stars are scattered in its path.”.

What is interesting about this result The opposite of the role one usually (not without reason) assigns to black holes says Gaston Gerbet, professor of theoretical physics in the UBA School of Exact Sciences and a researcher at Conicet. Because of its gravitational field, one would think that it either disintegrates or eats stars. It is difficult to swallow one, because although they have a very strong gravitational field, they are small. So the star should go straight to its center. But what is certain is that if it goes over “low” (and this has been seen), it can destroy it. But here it seems to be the opposite, in the sense that the black hole somehow helps form stars, albeit through a somewhat indirect process.

The discovery by Schott and Reims was possible because they were able to see in detail what is happening near the Hennes 2-10 black hole, with a resolution of each pixel of a few tens of light-years, very precisely. On a galactic scale, if we take into account that the stars that can be seen with the naked eye in the constellation Orion are hundreds of light-years away.

“The black hole in the center of the Milky Way is not very active, it doesn’t “accumulate” (accumulate or condense) a lot of matter – explains Geribet – but in Henize 2-10, there is a lot of activity. Matter approaches it, a very hot vortex is formed, ionization and bursts of energy are generated. It does not mean that the flow is coming out of the black hole (which can leave nothing out of it), but from the closest. The picture of the umbilical cord is very good, because it nourishes a birth, but it does not come out of the center of the black hole. This one is around it, very close to it, but outside, a halo of glowing matter emanating from that jet of energy that impacts a slightly farther region, about four hundred and fifty light-years away, where there is a lot of gas and dust. Usually stars form in these regions. They are like lumps that are generated from the accumulation of gases and dust. In a large galaxy, what you see is that matter and radiation are accumulating near the black hole. This jet, this kind of umbilical cord, is carried there as well, but when it hits the surrounding dust and dust, what it does is scatter it and, paradoxically, ends up suppressing star formation. But in this dwarf galaxy, that doesn’t seem to be the case. What you do nurtures and encourages star formation. It is similar to what happens when grilling, and if you give it a little air, the fire regenerates. But if you give it too much, it stops it. Something similar happens in the universe: in large galaxies, these outflows of energy hit the surrounding dust and gas, scattering them and hindering the process of star generation. In this case where the galaxy is smaller, the active nucleus fuels the fires it ignites.”

A decade ago, Henize 2-0 sparked a debate among astronomers about whether dwarf galaxies contain black holes that match the supermassive giants found at the cores of larger galaxies. Now, you can help solve this puzzle.

Although it has been theorized since 1915, the initial (albeit indirect) observational evidence for black holes dates back to 1964, but the first visible image was obtained in 2019. “Previously, very energetic phenomena have been discovered that could only be due to the presence of a black hole – highlights to the astrophysics world – gamma rays and X-ray emissions, for example. It took us a long time until we had enough observing power to see them. Soon, from The Event Horizon Telescope is expected to image the black hole at the center of our galaxy, and then we’ll have two.”

Henize 2-10 is considered a dwarf galaxy because its mass is twenty times less than the Milky Way.: It is estimated that the latter contains about two hundred billion stars, and the former has about ten billion. However, since 2011 it has been known to have in its center an extremely supermassive black hole of one million solar masses. “It was a surprise, because the mass in our galaxy, which is 20 times greater, has four million solar masses, and for a long time it was believed that black holes do not contain supermassive black holes,” the researcher comments.

It has also been suggested that black holes in the center of galaxies are related to their mass, but this has been verified in large holes. “For example – explains Giribet – if a galaxy is a hundred times heavier than the Milky Way, then the black hole in the center is usually a hundred times larger. This linear relationship between the mass of the galaxy and the black hole was a poorly understood law, but it seems to be true We now know that this relationship (at least sometimes) does not apply to dwarf galaxies.The Henness 2-10 black hole should be 20 times smaller than the Milky Way’s, but only slightly smaller.The same is true for the Leo Galaxy I dwarf, which also hosts a supermassive galaxy.”

Another unanswered question is Why are there black holes at the center of galaxies? There are various speculations. Given the proportion that has been identified between the two, it is believed that they must have played some role in their formation. “Black holes in the center of galaxies are very massive, they can be equal to millions or billions of solar masses; however, they are nothing compared to the total mass of these stellar structures. For example, Geribet suggests that the Milky Way has a black hole with four million solar masses, But it consists of hundreds of billions of the Sun. This means that the black hole does not “dominate” it dynamically. If you move it, it will not be enough to move the galaxy. Why do they end up in the center? It could happen that they were carrying stars around them in their course, and that they were Like some kind of funnel.There is something unknown. We are learning that dwarf galaxies also have very massive black holes and this will allow us, if we collect more examples, to clarify the role they play in the formation of galaxies from their birth. I think in the next 10 years we will understand it better“.