The first and most detailed map of black holes is available

The most detailed map of the universe’s black holes to date, each dot in the map indicates the location of a black hole, a total of more than 25,000.

At first glance, this map is no different from a starry sky map at night, dotted with stars. In fact, this is the most detailed map of black holes in the universe to date, showing the locations of more than 25,000 black holes.

Each bright spot is a black hole that is swallowing dust and gas around it, and these black holes are typically perched right in the middle of a galaxy. Their intense activity emits rays of various wavelengths that reach Earth and are detected by scientists to create this map.

Not every black hole is so active; some are so calmly hiding in space that scientists have a harder Time detecting them.

Even these intensely active black holes are not easy to detect and must be detected with the help of the Low Frequency Radio Telescope (LOFAR), which is spread over 52 sites in Europe and consists of more than 20,000 antennas.

LOFAR is currently the only telescope in the world capable of detecting low-frequency signals at frequencies below 100 megahertz. Radio waves traveling through space are constantly decreasing in frequency and losing energy. So the radio wave signal from millions of light years away to Earth is very weak, only highly sensitive instruments like LOFAR can detect.

Researchers said that the ionosphere of the Earth’s atmosphere is a huge difficulty for LOFAR. This layer ranges over a large area, from 50 kilometers above the ground all the way up to nearly 1,000 kilometers high in the sky, a region where the atmosphere borders the vacuum environment of outer space.

The ionosphere is rich in electrons and various charged particles that reflect radio waves from outer space at frequencies below 5 MHz back into space. For this reason, researchers have developed an algorithm run by a supercomputer that filters ionospheric interference every 4 seconds to collect radio signals.

This map is a compilation of difficult data that has been accumulated over many years,” said Francesco de Gasperin, an astronomer at the University of Hamburg (Germany). We had to come up with new ways to translate the radio signal into a photograph of the sky.”

The photo covers 4 percent of the northern hemisphere sky.

The study was submitted Feb. 18 to the preprint network arXiv and will be published in the journal Astronomy & Astrophysics.