There are galaxies in the Universe that have stopped producing stars. They are considered dead. Scientists had several theories about why this happens, but they could not be verified due to lack of information. The latest technical equipment helped to more accurately record the death of the galaxy and find its causes.
Astronomers have figured out that there are many dead galaxies in the universe. Among the reasons for their death – “gluttony” and the activity of dark matter. It turned out that this is not only a matter of age, but also of how the galaxy produces stars, how active it is. Understanding if this could happen with the Milky Way? How does the death of the galaxy take place? What are the causes of death?
Are there many dead galaxies or is this not a frequent occurrence?
Those galaxies in which stars have ceased to form are called dead. They have existed since the inception of the universe.
In one of the large-scale studies of dead galaxies, scientists from the Niels Bohr Institute found that almost 50% of all the largest galaxies in the Universe, 9 billion years ago, stopped producing new stars. This means that they can be considered dead.
How are dead galaxies formed?
To understand this, consider the Milky Way galaxy. At its center, presumably, there is a supermassive black hole: it is responsible for all the movements inside. Scientists believed that as soon as a black hole begins to behave more actively, then it throws out cold dust and hydrogen clouds, as a result, the galaxy collapses, and the process of star formation stops.
Further, gas clouds from the black hole envelop the galaxies and prevent gas flows from penetrating inside. The result is a cloud-walled galaxy that produces no stars.
There was also another opinion. Some astronomers believed that dead galaxies are formed due to collisions with each other. After such a sharp contact, an explosion of star formation occurs and the entire supply of gaseous hydrogen, with the help of which new stars appear, is at zero.
To understand the true reasons, scientists took pictures of the central part of the oldest galaxy MACS2129-1. At first glance, it is no different from the rest: it has ceased to form stars and has a red tint – it is a characteristic color for red dwarfs, which are almost out of material for internal thermonuclear reactions.
Further, the authors drew attention to the spectrum of the galaxy and found that it was not in the shape of a ball, but flat, somewhat reminiscent of the Milky Way. This means that the galaxy “perished” at the dawn of its development.
According to astronomers, this death was due to dark matter: it accelerated and warmed up ordinary matter, from which new stars are formed in the galaxy. Therefore, the star-forming material quickly ran out and all activity ceased.
Death from “gluttony”. How does the new theory of the death of galaxies work?
Different galaxies produce stars at different rates. To create one star, you need a special gas, which is in limited quantities.
Astrophysicists have discovered the CL J1001 + 0220 galaxy cluster located in the early universe. It annually forms such a number of stars that it is 4 thousand times heavier in mass than the Sun.
This is a record number. This rate of star formation will lead to the fact that gas reserves will run out and there will be nothing to create stars from. Such a phenomenon was jokingly called “death from” gluttony “”.
But despite their knowledge, scientists would not have been able to discover new similar objects if it were not for a large cluster of galaxies: it works like a lens and helps to study the distant regions of the Universe much more clearly.
Astronomers have published pictures of dead galaxies. The images show yellow light – it came from starlight. There is also violet light – this is cold dust: it appears instead of hydrogen gas, which is responsible for the appearance of stars.
The death of a galaxy depends on the type of its star formation, but this event can also happen quite unexpectedly, for example, due to the activity of dark matter. Astronomers have not yet studied all the causes of galactic death, but today there are enough tools to identify such objects and understand the causes of death.
Now scientists are engaged in classifying the causes of death of galaxies and highlighting the most likely and popular among them.
