This incredible image does not show a starry sky, but every white dot is a supermassive black hole at the core of a different galaxy.This ensemble was created not by visible light but from radio waves emitted by matter orbiting these huge and distant black holes. This is the most detailed sky map in low radio frequencies yet.
The radio observations were collected by the Low-Frequency ARray (LOFAR), a system of 52 stations spread over nine European countries: Germany, The Netherlands, Poland, France, the UK, Sweden, Ireland, Latvia, and Italy. Together they are the largest combined radio telescope in the world.
The observations were conducted in low radio frequencies. Long radio wavelengths are greatly affected by the ionosphere, the layer of electrically charged particles that surround our planet. The free electrons that make that layer are not good for these radio observations as their motion affects the quality of what astronomers can observe.
“This is the result of many years of work on incredibly difficult data. We had to invent new methods to convert the radio signals into images of the sky,” said lead author Dr Francesco de Gasperin from the University of Hamburg.
