Black holes that… shed light? Science stumbles in the dark

This phenomenon has been observed several times and is related to the falling of stars, but no one has yet been able to explain the phenomenon.

Ah, black holes! One of the greatest secrets of the universe! In fact, we know very little about it, because there is no way to observe anything other than the event horizon. Basically, there is no way to know what is happening inside a black hole, because it is also not visible, although we can image its shadow thanks to radio telescopes. When a celestial body is attracted to a black hole, it inevitably falls into it and cannot escape due to its very high density, which does not allow anything to escape, including light. But science wonders about a phenomenon for which it has not yet been able to provide an accurate explanation: Some black holes emit light!

Space spaghetti

How could such a paradoxical phenomenon actually occur before the eyes (or at least the telescopes) of astronomers? As mentioned earlier, when black holes contain something, usually a star, they light up, but this is a paradox. Stars, as we explained in an Ars Technica article that attempts to explain the phenomenon to non-practitioners, burn and emit light by virtue of the nuclear reactions that occur within them through… fusion. This process is the exact opposite of nuclear fission, i.e. the process of splitting the atom that is normally used to produce energy in nuclear power plants, even if there are experiments underway to try to create nuclear fusion reactors, which would be more efficient (but it is a long journey that will require many years of study and experimentation).

Nuclear fusion that occurs in stars consists of the union of the nuclei of two or more atoms that fuse together, releasing an enormous amount of energy in a transformative action that overcomes the electromagnetic repulsion of the atoms themselves. The reaction that occurs in celestial bodies is called exothermic precisely because it releases energy, and the nucleus of a molten atom is actually smaller than the nucleus of separate atoms.

The strangeness is that once a star enters the black hole's sphere of influence, it not only begins to fall into it, but “weakens”, so to speak, or rather submits to its influence. macaroni. This phenomenon is called Tidal destructionIn theory, it should prevent the star from continuing to emit light once it starts disintegrating: eventually, nuclear fusion reactions should stop. Instead, for reasons that remain unexplained, this does not appear to be happening, as the stars continue to shine and their line surrounds the spherical surface of the black hole, with the result that we are able to see and image it.

These are clearly phenomena in which radiation plays a role, but we don't know exactly how many and which ones, at what wavelengths they travel, how strongly they rise and fall, and ultimately what exactly causes them. Since there is no way to get close enough to a black hole to quietly study this phenomenon – and, moreover, tidal destruction does not occur frequently – the only solution is to develop software that can create simulations of this type of event. Various attempts have been made over the years, and they have not been very satisfactory. But now, a particularly promising program has been developed: RICH.

The search continues

At the Hebrew University, researchers Elad Steinberg and Nicholas Stone are conducting tests with the company RICH, which specializes in hydrodynamic calculations. Wondering what this has to do with stars and black holes? The fact is that the motions of the star as it collapses before merging into the black hole behave similarly to fluid mechanics: RICH is capable of measuring radiation emission and absorption capacities of liquidsWhich gives us models that can be compared to disturbances caused by tidal destruction.

By observing the behavior of a spaghetti star and entering the data into RICH, researchers were able to understand that when a stellar filament passes twice over the star, Ocean (The closest point separating it from the black hole) is this episode It causes turbulence due to shock waves of stellar material that makes up the gaseous volume of the filament itself. In essence, turbulent gases near the circumcenter emit radiationWhich we can observe and photograph using radio telescopes. This creates this bright circle around the event horizon, with a tail of filaments. Ars Technica effectively describes this stunning image as a kind of space spin.

Although simulations performed via RICH have given encouraging results in terms of general understanding of this phenomenon, it is too primitive a system to appreciate all the details. For example, RICH is unable to properly take into account the quantum mechanical effects that occur in this phenomenon, which instead would need to be taken into account in order to obtain more accurate and specific representations of individual cases of tidal destruction. What can I say, the research continues!