It is not uncommon for astronomers to find a black hole in the center of most galaxies, but it is still a theoretical matter that a galaxy has two black holes.
The team's research results were published in the Journal of Astrophysics, and the title of the paper was "Systematic search for the periodicity of gamma rays in active galactic nuclei detected by Fermi large-area telescope". (Journal of Astrophysics, "Systematic search for the periodicity of gamma rays in active galactic nuclei detected by Fermi large-area telescope." )
The study's main author, Palo Penile, Ph.D., CompRutans University, Rutans, Madrid? Il) said: "Generally speaking, supermassive black holes are characterized by a mass that is more than one million times that of the sun. Among these supermassive black holes, some are called active galactic nuclei (AGN), which can accelerate particles to collimated beams near the speed of light, called beams. The radiation of these beams can be detected in the whole electromagnetic spectrum, but most of their energy is released in the form of gamma rays.
Gamma-ray is the most critical light form ③, which can be detected by the large-area telescope on the Fermi Gamma-ray Space Telescope of NASA. The characteristic of AGN in active galactic nuclei is that the brightness suddenly changes unpredictably.
Penil said: "Identifying the law of their gamma-ray radiation is like looking at the rough sea and looking for a group of tiny regular waves caused by the passage of small boats." "This is really challenging."
The team has completed the difficult first step, that is, identifying a large number of galaxies that will emit gamma rays periodically for several years, and is trying to find out the reasons for their periodic (gamma ray emission) behavior in these AGNs. Some potential explanations are really interesting.
According to Fermi-LAT's ten-year observation, the team can identify gamma-ray signals that are repeated within several years. On average, these models are introduced about every two years.
Pe said: "Our research is the most complete work to discover the periodicity of gamma rays so far, and this research will help to deeply understand the reasons for this special behavior. ? Dr. Il's colleague Alberto dominguez, a former postdoctoral researcher in clemson's Aiello research team, said. . "We have been using LAT for all-weather observation for 9 consecutive years. Of the more than 2,000 active galactic nuclei studied, only about 12 stands out because of this interesting periodic radiation. "
Expanding these limited periodic emission samples is an important leap to understand the potential physical reactions in these galaxies.
"In the past, only two varieties ④ had periodic changes in gamma ray brightness. According to our research, we can confidently say that this phenomenon also exists in other 1 1 sources. In addition, our research also found 13 other galaxies with periodic emission signs. But to confirm this confidently, we need to wait for Fermi-Ratt to collect more data. "
Figure 1: schematic diagram of active galactic nuclei
Figure 2: Schematic diagram of a galaxy with two black holes.
(1): Collimated beam: a beam that keeps parallel between rays. Usually, light is divergent, that is, two adjacent lights will get farther and farther after they start diverging. Collimation is to keep the light parallel in common parlance.
②: Jet: the flow of particles or energy, and the thinner beam is also called ray.
③: Gamma rays may be called "the closest to the critical point" or "the most extreme" because of their extremely short wavelength, strong penetration and extremely high energy.
④ Yao variable star: high-density high variable star energy, which is assumed to be a supermassive black hole in the center of the host galaxy. Brightness is one of the most intense phenomena of celestial activity in the universe, and it has become an important topic in galaxy astronomy. Yao variant is one of many active galaxies, also known as active galactic nuclei.
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