It is always said that black holes They gobble up everything that comes close to themfrom matter to light. However, this is not entirely true. In some cases, there is a fraction of particles and energy that, instead of falling inside, does the opposite. It is ejected in the form of jets, known as jets. Although there are some hypotheses about this, the reason why this occurs is not completely known. What is known is that these jets are so powerful that they can even influence the evolution of galaxies.
The problem is that it is known that they are very powerful, but not how powerful. Until now, no one had been able to directly measure the power of these jets. However, an international team of scientists has achieved measuring these jets around a specific black hole, thereby opening up a very interesting range of possibilities.
The data. These scientists have studied the Cygnus X-1 systemcomposed of a black hole and a blue supergiant star orbiting each other. Using a very novel method, they have discovered that the energy of the jets leaving the black hole is equivalent to that of 1,000 suns. They have also observed that they move through space at a speed of 540 million kilometers per hour and that 10% of the energy that is initially formed in the fall towards the black hole is converted into jets.
The background. Until now, no one knew how to measure the power of a black hole’s jets. The only thing that was done was to measure the scars they left in space using calorimetric methods. When freed, they can leave in their wake hot spots and holes in the intergalactic medium. However, As explained in an article by Interesting Engineeringthis is something like wanting to measure the power of an engine by observing the treads of the car’s tires. The important thing is to directly analyze the machinery. And that is precisely what has been achieved now.
Indirect measures. In systems formed by a black hole and a star, the black hole feed little by little gas surrounding the star. As it approaches it, the gas begins to rotate faster and faster, generating a lot of heat and energy. Part of that energy does not fall into the black hole, but instead jump outward, forming the jets.
In turn, the star releases very intense flows of particles, which give rise to what is known as stellar winds. Those stellar winds can interact with the jets and bend them. And there is the key. The jets cannot be measured as such, but the resistance they offer to being bent by stellar winds can be measured. For example, we can know how strong a person is by analyzing his or her ability to beat someone whose strength we do know in an arm wrestling match.
Trajectory changes. The overall trajectory of the jets depends on the momentum flux of both the jets themselves and the winds. Since the momentum flow of the wind can be calculated, it is enough to analyze the trajectory to solve the unknown. The data can also be further refined with a series of computer simulations. The result is a fairly rough estimate of the power of the jets.
There are limitations. The biggest limitation of this study is that only one black hole has been analyzed. The procedure would have to be repeated with more jets in more black holes to check if there is a trend and, therefore, if the method is valid.
Galactic evolution. Since jets from larger black holes can significantly affect galactic evolution, this method could be very useful to better understand how galaxies form. That is why it is important to move on to the second step and check if the method is reproducible, especially with larger black holes.
Image| A supermassive black hole ejects a jet of plasma 3,000 light years long, traveling at almost the speed of light. NASA artist concept
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