Astronomers have known for several years that there is a direct relationship between the size of a galaxy and the size of the supermassive black hole at its center, but they do not yet know the reason for this relationship. A computer simulation at the Planck Institute showed that the growth of black holes releases a huge amount of energy that regulates the rate of star formation.
The larger the galaxy, the longer the process takes to occur so the black hole becomes larger.
Using a new computer simulation test, the study showed that the growth of black holes releases a tremendous amount of energy that regulates the rate of galaxy development and the development of the black hole itself. The model explains for the first time observations and gives an in-depth explanation of the process of formation and the cosmic role of black holes.
In recent years, scientists have learned that the amount of mass in stars in galaxies is directly proportional to the size of the black hole at the center of the galaxy, but until now it was not possible to explain the relationship obtained from the observations.
The key to the research breakthrough was introducing the dynamics of the black hole into a computer model of galaxy formation.
When a galaxy was formed in the early universe, it contained a relatively small black hole at its center, according to the standard scenario accepted for the process of galaxy formation, the galaxies grew due to the union between several galaxies due to the action of the gravitational force between them. In the process itself, the black hole at their center also merged and grew rapidly to the observed size of Billions of solar masses. Also, during the merger process, many stars were formed from the gas available today And the black holes in their center are the result of several such occurrences.
The researchers performed a simulation depicting a collision between two neighboring galaxies and found that when the galaxies merge, the two supermassive black holes merge and consume the gas surrounding them. However, this process is self-limiting, when the super massive black hole pulls the gas creates a state called a quasar, the quasar moves the gas around the level where it blows out into the galaxy, without gas the black hole cannot continue to "eat" to exist and becomes dormant. At this time there is also no gas available for the formation of more stars.
In the research it was found that the amount of energy released from a black hole during the quasar phase drives a strong wind that drives material to fall into the black hole, the process prevents the growth of the black hole and turns off the quasar, as well as the formation of stars in the galaxy, as a result the ratio between the masses of the stars and the black hole remains constant. This also explains why the lifetime of a quasar is shorter than the lifetime of a galaxy.
According to the research, black holes in small galaxies regulate their growth rate more effectively than in larger galaxies, small galaxies contain smaller amounts of gas than in large galaxies so that a small amount of energy from the hole is enough to stop material from falling into the hole and because the gas is wasted quickly, galaxies Small ones form few stars. In large galaxies, because the gas is present longer, they produce more stars, this finding verifies observations The links between the size of a black hole and the mass of stars in a galaxy.
The simulations demonstrate how self-regulation can give a quantitative explanation for observations, and gives an explanation for the lifetime of a quasar and can explain why quasars were more common in the young universe than today.
The research will continue to test models of a large number of galaxies and black holes and test their influence on the cosmic level.
