Sunday , January 24 2021

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

According to foreign media reports, astronomers have for the first time observed the final stage of the merger of galaxies. Through thick gas and dust, they saw pairs of supermassive black holes that were coming closer and growing rapidly after the collision.from

In the center of most, if not all, galaxies there 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, considered to be the closest supermassive black hole, about 4.5 million times the size of the sun.

In galaxy NGC 6240 you can see that in the final stages of the merger there are two smaller galaxies. The black holes in the core of the two small galaxies grow rapidly, consuming gas and dust that unite the galaxies.

Some of the galactic cores that are faced with are in the final stages of the merger. The top left is the NGC 6240 galaxy. The photo on the left is made of a Hubble Space Telescope's third-generation camera, and the picture on the right shows the galactic nucleus captured by the infrared beam Keck Observatory. "A Panorama Sky Telescope and a Rapid Response System," and the Keck Observatory.

Previous studies have found that fusion of galaxies can contribute to the growth of supermassive black holes. Researchers suggest that black holes in the center of collapsing galaxies can merge to form large black holes.

Merging galaxies is likely to provide enough room for super massive black holes to tear up the stars and swallow substances. This collision releases an extremely large amount of radiation and will probably be the driving force behind the quasar. Quasar is one of the most brilliant objects in the universe. However, the authors of this new article argue that the evidence supporting the super massive galaxy-based black hole growth model is very complex. Although some studies reveal a relationship between quasars and fused galaxies, other studies have not found such associations.

One possible explanation for the obvious lack of correlation between the quasars and the united galaxies is that the gas and dust surrounding these galaxies are likely to overshadow black holes. Even in the early stages of the merger, this is so when the distance between galaxies is more than 16,000 light-years. The authors of the study point out that computer simulations show that the degree of occlusion will be the highest in the final phase of the galactic fusion where the distance between galactic nuclei is less than 10,000 light-years.

Now the researchers have seen several galaxy pairs in the later stages of the merger, and the super massive black holes in their center are constantly approaching. These discoveries will provide clues on how to form larger supermassive black holes.

Researchers for the first time received 10 years of X-ray data from NASA's Neil Gehrels Swift Observatory to find information about hidden black holes. When black holes swallow substances, high-energy x-rays can be seen from these "active" black holes, even if they are blocked by dense gas and dust.

The researchers then looked at galaxies that coincided with X-ray information, combining data from the Hubble Space Telescope and the Keck Observatory (Hawaii, USA). The first author, Michael Koss, said the Keck Observatory could make the star more acute than a computer controlled deformable mirror by a technique called adaptive optics. "There is a big increase in the resolution."

Coase is an astrophysicist at Eureka Scientific Technologies in Auckland, California. He said: "This is equivalent to 20/200 eyesight (equal to what we call visual acuity 0.1), ie blindness in the legal sense, in a 20/20 vision (visual power 1.0) so that we see people incredible details of the galaxy. "

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

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

"Merging galaxies can be an important way to grow black holes," Coas said. The Milky Way we are in is currently in the process of merging with the neighboring Andromeda galaxy, and the supermassive black holes in the core of the two galaxies will eventually collide and merge. 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, "said Coase. In the 6 billion years, the Milky Way or the Fairy Galaxy will cease to exist, leaving only a larger galaxy. "

For galaxies hidden behind gas and dust, the clearer observations from them can come from NASA's James Webb Space Telescope. It is an infrared telescope that is expected to be launched in 2021. The next generation of astronomical ground-based telescopes such as the 30-meter telescope, the E-ELT and the Giant Magellan telescope will also be available to us through active optical systems . Bring a more detailed image of the galaxy. Researchers say the space telescope James Webb should also be able to measure the quality, growth rate and other physical characteristics of the supermassive black holes that are closer to us.

The results of the study were published in Nature 7.

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