(ORDO NEWS) — American astronomers, in an article published in the journal Nature Astronomy, reported the first detection of binary quasars. Two such objects were recorded at once by the Hubble Space Telescope in the early Universe. Each of them is at least 10 billion years old.
Quasars are some of the brightest objects in the visible universe. It is believed that they represent active galactic nuclei at the initial stage of development, in which a supermassive black hole absorbs the surrounding material, forming an accretion disk. It is the source of extremely powerful radiation, tens and hundreds of times higher than the total luminosity of all stars in galaxies such as ours.
Quasars are scattered throughout the universe. Basically, these are very ancient objects that were formed in the early stages of its development, but they are located so far away that their light reaches the Earth only now. Scientists believe that there are many binary systems among them, but only with the advent of the Hubble telescope it became possible to see two separate objects inside a very bright spot.
Double quasars were discovered by specialists from the University of Illinois at Urbana-Champaign. First, using observations from the European Space Agency’s Gaia space observatory and data from the Sloan Digital Sky Survey, they compiled a list of possible quasar pairs in the early universe.
First of all, they singled out those objects that showed slight oscillatory movements. These fluctuations, according to the researchers, could indicate random fluctuations in light, since each member of a pair of quasars changed brightness. Then the Hubble was pointed at them. Of the four targets set, two were confirmed.
“According to our estimates, in the distant Universe, there is one double for every thousand single quasars,” the first author of the article, Professor of Astronomy Yue Shen, quoted in a press release from the University of Illinois. “So finding these double quasars is like a needle in a haystack.”
The authors believe that quasars located next to each other are located in the centers of merging galaxies, and over time can unite into supermassive black holes, while generating gravitational waves.
Hubble images show that the quasars within each pair are only about 10,000 light-years apart. By comparison, the Sun is 26,000 light-years from the supermassive black hole at the center of our Galaxy.
“Quasars have had a tremendous impact on the formation of galaxies in the universe,” says fellow research participant Nadia Zakamska of Johns Hopkins University in Baltimore. “Finding binary quasars in this early era is important because we can now test our long-standing ideas about how black holes and their host galaxies evolved together.”
Scientists are confident in their result, although they say there is a small chance that the Hubble images captured double images of the same quasar, separated by gravitational lensing. This phenomenon occurs when the gravity of a massive foreground galaxy splits and amplifies the light from the background quasar into two mirror images. However, the researchers say this scenario is unlikely because Hubble did not detect any foreground galaxies near the two pairs of quasars.
To verify the correctness of their results, the authors conducted additional observations using the Gemini telescopes of the NOIRLab National Research Laboratory for Optical Infrared Astronomy, which confirmed the scientists’ conclusions.
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