The previous view of a black hole as a kind of object that does not let go of even light from itself has now been refuted. A striking, in every sense, an example of this is the result of the first stage of operation of the LOFAR interferometer, which consists of 20,000 stations located throughout Europe. The image created with its help shows a section of the starry sky, where the white dots are supermassive black holes that look exactly like this in the ultra-low frequency range.
In fact, everything turned out to be much more complicated: black holes really remain black while they are in the void of space. But starting to attract other objects to themselves, they destroy matter, which generates not only a luminous cloud of gas and dust, but also many sources of radiation at different frequencies. This is exactly what happens in the centers of distant galaxies, of which at least 25,000 are captured in this image.
The difficulty of observing such objects is that the Earth’s ionosphere is opaque for radiation at frequencies below 5 MHz. And those of its species that penetrate through it are greatly distorted due to atmospheric phenomena. It was the development of an algorithm for correcting these interference that became the main difficulty of the LOFAR project, the implementation of which took many years. But now scientists have in their hands a tool that allows them to work with cosmic radiation at frequencies below 100 MHz, and even below 50 MHz, which is still a complete “terra incognita”.
Noise correction occurs every 4 seconds, so the first 256-hour shot required the use of multiple supercomputers. The presented image contains only 4% of the northern sky, and scientists already have a list of more than a million targets – a variety of sources of ultra-low-frequency radiation in distant space. In addition, LOFAR has a useful side effect – its algorithms for analyzing the state of the ionosphere allow you to simultaneously study and her.