About 75,000 active galactic centers — supermassive black holes feeding on matter — have been identified in a new technique. The research authors used 3D maps of galaxies in some specific parts of the sky, created by Australian scientists.
How to see a supermassive black hole
When a supermassive hole in the center of a galaxy feeds on clouds of gas and dust, or even a star, some of the matter is accelerated and starts to rotate around the object at high speed, forming the accretion disk. In many cases, the black hole’s magnetic field creates relativistic jets with some of that matter.
This entire process releases a lot of energy, so many black holes can be detected, even though they are invisible. Technically, they don’t emit radiation, but they turn your food into veritable “soups” of superheated, glowing plasma.
Want to catch up on the best tech news of the day? Access and subscribe to our new youtube channel, Kenyannews News. Every day a summary of the main news from the tech world for you!
This glow, however, appears only in certain specific bands of the electromagnetic spectrum, often in radio waves. So when this process takes place in a supermassive black hole at the center of a galaxy, scientists call it a “radio galaxy”.
To find these emissions, scientists use instruments that “see” radio waves, but it doesn’t always work. It is that some active galactic centers also emit radiation at other wavelengths, such as X-rays—sometimes without any radio emission.
Technique detects active galactic centers
The authors of the new study devised a method to identify galaxies that have an active center, that is, a central supermassive black hole feeding on matter. To do this, they turned to 3D maps created by Australian astronomers, which span 11 billion light years.
700,000 galaxies have been identified on these maps, and more than 75,000 of them have an active nucleus. They used the spectral energy distribution, which is the relative brightness of a galaxy in different parts of the electromagnetic spectrum. According to the authors’ statement, this data can be used to measure how many stars there are in a galaxy or their age, for example.
This result is not yet definitive — the team needs to make sure that all active galactic centers have been identified in the 11 billion light-years covered by the maps. Once this is accomplished, astronomers will be able to better understand how central black holes influence evolution and even contribute to the end of star formation in galaxies.
The study was published in the Monthly Notices of the Royal Astronomical Society.
