Astronomers for the first time observe the final stage of galaxy fusion – Science Exploration –


According to foreign media reports, astronomers have for the first time observed the final phase of galaxy fusion. Through thick gas and dust, they saw pairs of supermassive black holes approaching more and more, and growing rapidly after the

At the center of most, if not all, of the galaxies are supermassive black holes whose mass is millions to billions of times the sun. For example, Sagittarius A * in the center of the Milky Way is a very bright and dense source of radio waves, supposedly the nearest supermassive black hole, about 4.5 million times the size of the sun.

In the galaxy NGC 6240, you can see that two smaller galaxies are in the final stages of fusion. The black holes in the center of the two small galaxies are growing rapidly, consuming the gas and dust that fuse the galaxies.

Some of the galactic nuclei that are colliding are in the final stages of fusion. At the top is the galaxy NGC 6240. The image on the left is taken by the third-generation Hubble Space Telescope camera. The image on the right shows the galactic nucleus photographed by the Keck Observatory with infrared rays. The images from the four galaxies below are translated by Pan-Star program. "Sky Panoramic Telescope and Rapid Response System" and the Keck Observatory.

Previous studies have found that galaxy fusion can contribute to the growth of supermassive black holes. Researchers suggest that black holes in the center of colliding galaxies can fuse to form larger black holes.

The merging of galaxies is likely to provide ample opportunity for supermassive black holes to pull stars and devour substances. This collision releases an extremely large amount of radiation and is likely to be the driving force behind the quasar. A quasar is one of the brightest objects in the universe. However, the authors of this new article say that the evidence supporting the supermassive growth model of the black hole based on galaxies is very complicated. Although some studies have revealed a connection between quasars and fused galaxies, other studies have found no such associations.

One possible explanation for the apparent lack of correlation between quasars and fused galaxies is that the gas and dust surrounding these galaxies will likely obscure the black holes severely. Even in the early stages of fusion, this is the case when the distance between galaxies is more than 16,000 light-years. The authors of the study point out that computational simulations show that the extent of this occlusion will be greater in the final phase of galactic fusion, where the distance between galactic nuclei is less than 10,000 light-years.

Now researchers have looked at several pairs of galaxies in the final stages of fusion, and the supermassive black holes at its center are constantly approaching. These findings will provide clues about how supermassive black holes are formed.

The researchers obtained 10 years of X-ray data from NASA's Neil Gehrels Swift Observatory to examine information on hidden black holes. When black holes devour substances, high-energy X-rays of these "active" black holes can be observed even if they are blocked by thick gases and dust.

The researchers then analyzed the galaxies that matched the X-ray information, combining data from the Hubble Space Telescope and the Keck Observatory (Hawaii, USA). The first author of the article, Michael Koss, said the Keck Observatory could make the image of the star sharper by a computer-controlled deformable mirror through a technique called adaptive optics. "There is a huge increase in resolution."

Coase is an astrophysicist at Eureka Scientific Technologies in Oakland, California. He said, "This equates to a 20/200 vision (equal to what we call a visual acuity of 0.1), that is, blindness in the legal sense, in the 20/20 vision (visual power 1.0), so that we can see People Details of the Unbelievable Galaxy ".

In all, the researchers analyzed data from 96 galaxies observed by the Keck Observatory and 385 galaxies observed by the Hubble telescope. The average distance between all these galaxies and Earth is 330 million light-years, relatively close to the cosmic scale, and many galaxies are similar in size to the Milky Way.

The researchers found that more than 17% of these galaxies have a pair of black holes in the center, indicating that they are in the final stages of galaxy fusion. These findings are consistent with the researchers' computational simulations, which show that active black holes hidden in galaxies rich in gas and dust are the cause of the merging of many supermassive black holes.

"Fusion galaxies can be an important way to grow black holes," Coase said. The Milky Way we are currently in is merging with the adjacent Andromeda Galaxy, and the supermassive black holes in the nuclei of the two galaxies will eventually collide and fuse. Now, there are millions of light years between the two galaxies, but we (the Milky Way) are moving toward the Andromeda galaxy at a speed of 400,000 kilometers per hour, "Coase said. In 6 billion years, the Milky Way or the Fairy The galaxy will cease to exist, leaving only one larger galaxy. "

For galaxies hidden behind gas and dust, their clearest observations may come from NASA's James Webb Space Telescope. This is an infrared space telescope due out in 2021. Next-generation terrestrial astronomical telescopes, such as the Thirty-Foot Telescope, the Extremely Large European Telescope (E-ELT) and the Magellan Giant Telescope, will also be available to us through of active optical systems. Bring a more detailed picture of the galaxy. Researchers say the James Webb Space Telescope should also be able to measure the quality, rate of growth, and other physical characteristics of the supermassive black holes that are closest to us.

The study results were published in the Nov. 7 issue of Nature.


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