The flash of black holes is related to their mass

In the cores of galaxies there are so-called “supermassive” black holes, the masses of which range from several hundred thousand to billions of solar masses. The Milky Way is no exception, with the Sagittarius A* black hole at its center and four million solar masses. The gravitational force that prevails in such objects that nothing can escape from them outside a specified radius called the “horizon”. Not even the light.

Around the black hole, matter accretion disk

Gas and dust accumulate around the black holes, which gradually swallow them, and this substance takes the form of an accretion disk. It is compressed and heated there to extreme temperatures before falling into the belly of the black hole. This phenomenon It generates many side effects, such as the creation of a magnetic field of the accretion disk, or the emission of X-rays, which are then detected by measuring instruments.

A study dating back to 2020 saw a note flash from this disc. These ephemeral pieces correspond to random fluctuations in the process of feeding the black hole around which the disk is forming, but the detailed process remains unknown to this day. Recently, a team from the University of Illinois led by researchers Colin Burke and Yu Shen discovered an interesting fact about this flash: it is related to the mass of the black hole. Their findings were published on August 12, 2021 in the journal Sciences.

Thanks to these new results, it will be possible to infer the mass of black holes by observing the light emitted by their accretion disk. So a new method for calculating the mass of black holes will be born, making it possible to pave the way for future research.

How does the nutrition of black holes relate to their mass

If this flickering of black holes is confirmed, the reason for this is still unknown. A previous study hypothesized a link between the mass of black holes and these differences in luminosity, the time scale of which can vary from a few hours to decades. “Several studies have explored possible relationships between observed flicker and . mass giant black holeBut the results were inconclusive and controversial at times.”Colin Burke, first author of the study, said in a communication.

To establish the confirmed link between oscillating black holes and mass, the team of researchers has compiled a well-known data set of supermassive black holes. Thus they targeted 67 active galactic cores that harbor black holes, covering a large mass range from ten solar masses to several billion. The glamor of each has been detailed and, above all, the time differences of that brilliance. There they found a linear relationship between the mass and timeline properties of these black holes.

A discovery that also applies to white dwarfs. Maybe for other things too

But their research does not end there. The team wanted to test this relationship between mass and luminosity by extending it to lighter astronomical objects, which also contain an accretion disk: white dwarfs. These correspond to the remains of dead stars, which weighed less than four solar masses during their lifetime. As with black holes, the material that absorbs them forms an accretion disk, which is also a source of variations in luminosity. Surprisingly, the association between black holes also applies to these stellar remnants ! “These results indicate that the processes that cause blinking during accretion are global, whether the central object is a supermassive black hole or a much lighter white dwarf.”Yu Shen, professor of astronomy at the University of Illinois and co-author of the article.

Their results pave the way for a lot of research, first of all regarding the complex physical processes that occur in accretion disks, but also everything related to the discovery of black holes, which remains a challenge for them. Because beyond the horizon, nothing escapes, neither matter nor even light. To discover the existence of such an object, it is not necessary to look at it head-on: rather, scientists note the influence that it exerts on the stars and gases surrounding the black hole. Thus, stellar black holes, called “small” black holes (a few solar masses), can be detected thanks to their influence on nearby stars. The faster the stars rotate around them, the greater the mass of the black hole.

Discover previously hidden black holes, thanks to their flash

Supermassive black holes, located in the center of massive galaxies, can be detected, according to the same principle, by the influence that they exert on nearby matter. The highly active galactic core, which surrounds the central supermassive black hole, is made up of rotating gas and dust – this is what makes up quasars. These galactic cores emit much more light than the rest of the galaxy, making them easily visible to our detectors.

Then all the inhabitants remain in the middle, the so-called “intermediate” black holes. This cluster has a mass of a few hundred to a few hundred thousand the mass of the Sun, and can be the source of supermassive black holes. Although they are present in number in our universe (there are approximately 45,000 in the Milky Way), they remain practically elusive because no detection method is effective at finding them. The discoveries of such stars can be limited to the fingers of one hand and it is a matter of luck: the first was confirmed in 2020 thanks to the detection of gravitational waves by the Virgo detectors in Italy and Lego in the United States. The black hole, consisting of 150 solar masses, is caused by merging stellar black holes, which by rotating one around the other create waves of space-time distortion. Then in 2021, another intermediate black hole was discovered thanks to Gravitational lensing effect, where the distortion of light as it passes close to a very massive object is called. But thanks to the researchers’ discoveries, a new method of detection could be born.

“Now that there is a correlation between the flicker model and the central body mass, we can use it to predict what a flickering signal might look like. medium-mass black hole“Burke said. As of the end of 2023, the Vera C. Rubin Observatory in Chile will scan the sky for the luster of billions of objects, and will collect an incalculable amount of data. An observational campaign that may make it possible to discover new intermediate black holes. Exploiting the data set Collected To find compatible flashing patterns Intermediate black holes Will be allowed To fully understand this enigmatic group of black holes has been sought.”said Shane Leul, professor of astronomy at the University of Illinois and co-author of the article.