NASA astronomers were the first to measure the diameter of the «donut» of black holes

© NASA / SOFIA/Lynette soochak the artist imagined a black hole, accretion disk and a surrounding ring of dustNASA astronomers were the first to measure the diameter of the «donut» of black holes© NASA / SOFIA/Lynette Cook

A donut of dust surrounding supermassive black holes in the centers of all galaxies turned out to be extraordinarily compact and hot, say astronomers from NASA, published an article in the journal MNRAS.

«Using the SOFIA telescope, we were able to obtain the most detailed images of the surroundings of a black hole that only you can prepare for these wavelengths. They allowed us to learn a lot about how «doughnut» of dust surrounding the Central part of the core of several galaxies,» said Lindsey fuller (Lindsay Fuller) from the University of Texas at San Antonio (USA).

Fuller and her colleagues are involved in a unique project of NASA and the German space Agency DLR is the world’s only flying Observatory SOFIA,which is a «Boeing 747» mounted with a 2.5 meter optical and infrared telescope. The rise of the telescope to a height of 13 kilometers allows to make the quality of the resulting images is close to the level of space observatories.

It tells the astronomer, her team tried to find the answer to one of the «eternal» questions of astronomy – do all black holes in the centers of galaxies have the same structure.

As of today, say the astronomers, in the center of each galaxy resides a supermassive black hole, constantly absorbing the gas and dust from the accretion disk – shaped accumulation of matter immediately surrounding it. Some of this gas and dust ejected by the black hole in form of jets, thin bundles of gas, accelerated to nearly the speed of light and emit huge amounts of energy in the form of light and x-rays.

Theoretical calculations show that the black hole and the accretion disk, in turn, should be surrounded by a very dense and thick «donut» of gas and dust, which prevents the propagation of the jet and rings of dust. Because of this similar galaxy can look quite different if we look at them from the side or top. Some astronomers do not think so and suggest that differences in the appearance of «quiet» and «bright» galaxies are associated with yet unknown features in the structure of their nuclei.

Fuller and her colleagues tried to understand, whether so it actually, trying to directly measure the radius of the «donut» for several different galaxies with SOFIA, and comparing the obtained data with results of theoretical calculations.

These observations uncovered a few unexpected things. First, it turned out that the real diameter of the dust «coats» of black holes is approximately 30% smaller than predicted by the theory describing their behavior. Secondly, the scientists found that this «donut» devotes far more energy than indicated on the past observations, as most of its infrared radiation is absorbed by water molecules in the Earth’s atmosphere and telescopes just didn’t see him.

Both, as the researchers note, may indicate that modern ideas about the behavior of black holes and their «bagels» may not be entirely true. To verify these suspicions, the researchers plan to hold a new session of observations of the galactic cores at other wavelengths. This will help them precisely measure the diameter and to study the internal «coat» of black holes and understand how it affects the radiation of the accretion disk and jets.