KOMPAS.com – The image above may look like a normal night sky filled with stars.
However, each of the white dots turned out to be not stars, but holes black hole active supermassive.
As quoted from Science Alert, Monday (22/2/2021) researchers used Low Frequency Array (LOFAR), an interferometric network of approximately 20,000 radio antennas spread across 52 locations across Europe to detect these black holes.
LOFAR is the only network radio telescope capable of deep, high-resolution imaging at frequencies below 100 megahertz.
The results from the detection using ultra-low radio wavelengths were surprising, as researchers found at least 25,000 supermassive black holes.
When not active, black holes do not emit radiation that can be detected. This makes black holes even harder to find.
However, when a black hole is actively accreting matter or expelling the disk of dust and gas that surrounds it, that force produces radiation at several wavelengths that we can detect across the vastness of space.
“This is the result of years of work with very difficult data. We had to find a new method to convert radio signals into images of the sky,” explained Francesco de Gasperin, an astronomer at the University of Hamburg Germany.
While the map covers only four percent of the northern sky. But researchers next plan to map the entire northern sky.
Furthermore, observation using LOFAR does not mean that there are no obstacles at all. Researchers say that LOFAR gets interference from the ionosphere.
So to solve this problem, the researchers used a supercomputer running an algorithm to correct ionosphere disturbances every four seconds.