Demystifying: What exactly is the production of galaxy gamma ray sources?

Unexpectedly beating

The images taken by the Qiantra X -ray Observatory satellite indicate that there is radiation from the surroundings of the large -scale black hole (Huma seat A*) in the center of the Milky Way. At the same time, this photo also shows more than 2,000 other X -ray sources in the area in the area.

Illustration: Huma seat A*is the bright and very compact astronomical power supply in the center of the Milky Way. It is a large quality black hole in a large quality black hole. It is similar to the large quality celestial body of the center of spiral and ellipse galaxy. Picture source: wikimedia.

In the direction of people and horses, the center of the galaxy is about 27,000 light years away from us. As scientists knew earlier, the Milky Way Center did have a large quality black hole surrounded by millions of stars. All these stars gathered more than the stars of the galaxy's outer arms near the galaxy near our solar location. close.

Observation data shows that there is a strong energy source in somewhere in this dense area -gamma ray source (astronomers are still trying to confirm). This powerful energy source may come from an explosive star, or a sign of a mysterious dark matter.

In the early spring of 2004, two gamma ray experiments (the Veritas project in the United States and the CANGAROO project in cooperation between Japan and Australia) confirmed the source of gamma rays. The recent detection results of the European high -energy three -dimensional vision system (HESS) have undoubtedly stated that the unexpected gamma rays were issued from the center of the galaxy.

After knowing these discoveries, Veritas's chief researcher Trevor Weekes couldn't help saying: "This is a bit surprising. Although the Galaxy Center has always been a mystery."

Some of this inference is based on this fact that the center part of our galaxy is covered by the dust on the plane of the galaxy, and the track of the sun and most galaxy alien planets is just under the cover of dust.

These dust absorbed a large number of visible light, making it almost impossible for people to see the center of the galaxy. But other forms of light, such as gamma rays (the highest energy type), will not be affected. This is one of the reasons for scientists to study gamma rays -gamma rays can penetrate dust to reach our solar system.

Shower detector

Three observatory are now recording high -energy gamma rays. Paula Chadwick, a member of the European University of Dellen, is a member of the European High -Energy Corusted Visual System (HESS) members, also said that Gamma rays are 1 billion times the hospital's X -ray radiation.

Fortunately, these high -energy photons are absorbed by the upper level before reaching the surface. Therefore, astronomers have taken this absorption as a way to detect gamma rays.

Weekes explained: "At a high altitude of about 20 kilometers, gamma rays will interact with air molecules to generate a pair of positive and negative electrons in the same direction with gamma rays."

Positive electron is an anti -substance of electronics. After the initial particle collides with other air molecules, more electron-positive electron pairs will be generated. This class forms the so-called "air cluster".

Generally speaking, a blue flash released by the fast -moving shower particles is weak, high -speed, and invisible to the naked eye. But large -scale collection mirrors such as European high -energy stereo visual systems (HESS) and other devices can capture the characteristics of shower.

Daniel Hooper, the theory of Oxford University, said: "From [Flash Detective], you can distinguish the direction and energy of entering and leaving gamma rays."

Black hole injection

By recording a variety of flashing from the same direction, astronomers have inferred that strong energy existence in galaxies outside millions of light years. One light year is the distance between the year alone, about 600 billion miles (100 billion kilometers).

These gamma rays may come from a large -quality black hole in the center of the distant galaxy.

In view of the large quality black hole in our galaxy, we have its own high -quality black holes, this black hole is likely to have a gamma ray jet to us.

Weekes said: "This will be an exciting result, but we don't have any evidence about the centers of the galaxy center."

One problem that still exists is that the radio and X -ray radiation of black holes is difficult to be consistent with the jet hypothesis.

Hu Bo said: "Frankly speaking, no one predicted that the black hole will accelerate the particles in this way."

Nevertheless, there are still some theories that try to imagine the necessary gamma rays without disturbing other constraints.

Supernova

Another possibility is that gamma rays come from the explosion or supernova of stars near the center of the galaxy.

Chadwick said: "We all know that a huge supernova exploded in this area 10,000 years ago."

The energy from such a star disaster will produce a shock wave -a bubble of expansion composed of high -energy particles. Therefore, these celestial bodies, known as the "supernova", are all over our galaxy.

In fact, the brightest gamma ray source in space is a crab -like nebula, which is the supernova relic after a star explosion in 1054. The brightness of the Gamma rays of the crab -shaped nebula is about 20 times that of the center of the galaxy, but the distance between the galaxy is about four times that of the crab -shaped nebula. Weekes said that the supernova wreckage has a variety of different energy spectrums, but the spectrum from the center of the galaxy looks similar to the spectrum from crab -shaped nebula. The spectrum is a rainbow produced by light. When it passes through the prism, it can be analyzed by chemical characteristics and other clues about light sources.

"The most conservative explanation is that [light source at the center of the galaxy] is a supernova." Weekes said.

However, the cooperative team of European high -energy three -dimensional vision system (HESS) said that just like black holes jet, the method of X -ray and radio measurement of supernova of the galaxy centers was used to modify the galaxy center supernova.

Dark material annihilation

Another possibility is that the gamma rays in the center of the galaxy are caused by the collision and self -destruction of dark matter particles. Celestial physicists have proven that this unknown dark matter is necessary to prevent spinning galaxy -just like gravitational glue that can prevent the clay from slipping from the over -rotated potter. Essence

A popular theory about dark matter involves an extension of the super -nominated (SUSY) -particle physics standard model (considers that each known particle has an ultra -symmetrical partner). Although there is no detection of supernovas, theoretically, some companions may be dark matter.

If we believe this situation, then our galaxy swims in a huge ultra -symmetrical particle group. Hooper explained that the density of the center of the particle group is very huge, and it may occasionally annihilating the ultra -symmetrical particles in the collision.

This annihilation will produce gamma rays. The spectrum detected by the European high -energy three -dimensional vision system (HESS) shows that there is a superior granular particle with a mass of 12,000 times the mass. The size of this quality may make scholars who support the ultra -symmetry theory feel uncomfortable.

Hooper said: "To allow the superior particles to achieve such high quality, you need to fine -tune other parameters to achieve a very delicate balance."

But Hooper did not completely rule out the possibility of dark matter.

Hooper said: "It may be something we have never thought of." At the same time, he also pointed out: "It must be a very strange thing, and the superior symmetry is not so strange."

Hooper emphasized that even if gamma rays do not come from annihilation, "the existence of dark matter is beyond doubt."

The final solution

To reduce the gaming versions of gamma rays, more data support is required. Because the air clustering detector must see the blue flash, they can only work on the moonless night. According to Weekes, only a few gamma rays per minute can reach the detection office from the center of the galaxy. It takes more time to collect the flash that can get a clear signal.

The European high -energy stereo visual system (HESS) in Namibia, located in southwestern Africa. In the summer of 2003, only two telescopes were observed in the center of the galaxy. The device is now equipped with four telescopes. The increased equipment will help the exact distinction of gamma rays.

Hooper said: "The problem has been developing forward, and the current discovery is just the corner of the iceberg -we expect that it will make steady progress in the next few years."

By: Michael Schirber

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