Unusual repetitive radio flares in the constellation Auriga, which some scientists believe to be signals of alien origin, do not originate in the Milky Way, but in a galaxy several hundred million light-years from Earth, according to an article published in the journal Nature.
“Without even knowing what they are, the discovery of the source is a real leap forward in uncovering the nature and origin of FRB outbreaks. The hunt for such radio bursts continues,”astronomer Heino Falcke from the University of Nijmegen (Netherlands) commented on the discovery.
Signals from the void
For the first time, astronomers started talking about the existence of mysterious bursts of radio emission (fast radio-burst, FRB) in 2007, when they were accidentally discovered during observations of radio pulsars with the Parks telescope (Australia).
In subsequent years, scientists managed to find traces of nine more such bursts, a comparison of which showed that they can be of artificial origin and even potentially be signals of extraterrestrial civilizations due to the inexplicable periodicity in their structure.
This spring, scientists discovered that the source of one of these FRB flares was an elliptical galaxy located 6 billion light-years from the Milky Way, leading them to conclude that such bursts are born during the merger of neutron stars or other compact objects that turn into black hole. Subsequently, astrophysicists discovered that FRB flares are repeated, thereby calling these theories into question.
Paul Scholz of McGill University (Canada) and his colleagues, who discovered these repetitive "alien signals", were able to localize their source by observing new FRB flares at the point from which the FRB 121102 burst discovered at the observatory came to Earth Parks in 2012.
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As Scholz explains, most FRB bursts were discovered by telescopes that "look" at a very wide part of the night sky, making their exact position extremely difficult to determine, even with a repetitive signal.
For this reason, Scholz and his colleagues observed FRB 121102 using the powerful 300-meter Arecibo telescope in Puerto Rico and the VLA interferometer, which allows determining the position of the source with an accuracy of a tenth of a second of arc.
Mysteries of space
Astronomers had only 83 hours to make observations with the VLA, but they split them in a very cunning way into six months, observing the point where FRB 121102 supposedly came from. Thanks to this, they were able to record nine bursts at once emanating from the same point and related to FRB 121102.
It turned out that this signal comes from the constellation Auriga, from a point near which there are several large galaxies and star clusters in our Galaxy. But the source of the flares itself is located in another object - in a dim galaxy, invisible to us in the optical range, at least 140 million light years from Earth. As shown by observations of it with microwave telescopes, stars are almost not formed in it, and the galaxy itself is extremely small.
Further observations of this galaxy showed that it constantly emits in the radio range, periodically flashing and generating flares similar to FRB 121102. Their source is a compact object in the center of this galaxy, the characteristics of whose radiation virtually exclude the possibility that it was generated by some objects inside the Milky Paths.
The nature of this radiation is still unclear - the point nature of its source speaks in favor of the fact that such flares give rise to black holes, but the absence of X-ray radiation at that point FRB 121102 speaks against this idea. Similarly, FRB bursts cannot be generated by supernova remnants due to differences in their spectra.
As astronomers suggest, "radio signals from extraterrestrials" may arise from the interaction of a neutron star and the supermassive black hole around which it revolves. On the other hand, the lack of periodicity in FRB flares casts doubt on this idea as well. Therefore, scientists hope that further observations of the galactic nucleus and the source of FRB 121102, as well as other flares of this type, will help to understand how they are born and who or what sends them to Earth.
