The theoretical possibility of the existence of black holes follows from the solution in 1915 by Karl Schwarzschild to some of the equations of Albert Einstein. Today we know that there really are regions of space-time in space, the gravitational attraction of which is so great that no objects, including photons of light, can leave them. In 2016, a team of physicists managed to hear and record the sound of two black holes colliding billions of light-years from Earth – this discovery finally confirmed the prophecy of Einstein s general theory of relativity. And just three years later, the world saw the first image of the shadow of a black hole located in the center of the galaxy Messier 87 (located at a distance of 55 million light years from our planet). As technology advances rapidly, sophisticated modern instruments and space exploration probes enable scientists to detect and study these space monsters, it is time to map them, freeing ourselves of the potential for being close to a black hole. If we, of course, someday can swim so far into the cosmic ocean.
How were black holes placed on the map?
Despite the triumphant discoveries of recent years, black holes are extremely difficult to detect, especially if they do not emit any radiation. They can be identified when materials such as dust and gas revolve around black holes, as the intensity of the accretion process generates radiation that can be detected from Earth. Recently, with the help of the world s largest network of radio telescopes LOFAR, astronomers have finally discovered a huge number of space monsters.
To date LOFAR Is the only radio telescope capable of detecting and capturing high-resolution images of supermassive black holes (emitting frequencies below 100 megahertz). It is noteworthy that LOFAR consists of 52 stationslocated in nine countries: France, the Netherlands, Poland, Great Britain, Germany, Latvia, Italy, Sweden and Ireland and is a joint project of the Dutch Institute of Radio Astronomy ASTRON and the universities of Amsterdam, Groningen, Leiden, Nijmegen, as well as the German consortium GLOW.
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Covering just four percent of the northern sky, LOFAR intends to map the entire observable area in ultra-low light frequencies, but this will not be an easy task since all LOFAR stations are based on Earth. In efforts to detect ultra-low-frequency radio waves, the planet s ionosphere – the layer of Earth s atmosphere filled with charged particles – presents a formidable challenge, distorting low-frequency signals coming from space. This makes it extremely difficult to detect black holes emitting frequencies below 5 megahertz. The complexity of the task is compounded by atmospheric conditions, which can change from time to time.
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To help astronomers pinpoint the location of these ominous objects, an international team of scientists led by researchers from the Netherlands Leiden University recently submitted a comprehensive map for publication in the journal Astronomy & Astrophysics. pinpoints the location of 25,000 supermassive black holes…
“With LOFAR, a new and handy tool, astronomers and astrophysicists can observe the night sky covered in brilliant white lights, each of which is a real black hole, illuminated by the radio emission of doomed matter, absorbed and discarded after a close collision,” write the authors of the scientific work …
According to Phys.org, the authors of the new study observed distant galaxies at radio frequencies from 42 to 66 megahertz. In general, the unique space cartography required more than 256 hours of observation and additional years of analysis. The study involved 52 LOFAR stations located in nine European countries.
“This is the result of years of work on incredibly complex data,” said study leader and former Leiden University scientist Francesco de Gasperin in an official press release. “We had to invent new methods of converting radio signals into images of the sky.”
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To gather data on black holes and place each candidate in their putative galaxy, the scientists used supercomputers augmented with new algorithms to correct the distorting effect of the ionosphere every four seconds. Study co-author Reinu van Veren of the Leiden Observatory explains that the effect is like trying to see the world from the bottom of a swimming pool, where surface waves affect your vision, deflecting light rays and altering the clarity of the picture.
In the future, with the help of the LOFAR telescope and supercomputers, astronomers hope to detect objects with radio frequencies below 50 megahertz and plot the entire northern celestial hemisphere on it. Will wait!