Hubble discovers a mysterious black hole disk

Astronomers using the NASA / ESA Hubble Space Telescope have observed an unexpected thin disc of matter surrounding a supermassive black hole in the heart of the spiral galaxy NGC 3147, located 130 million light-years away.

Astronomers are surprised by the presence of the black hole disk in an active galaxy that is so dim. Black holes in certain types of galaxies such as NGC 3147 are considered hungry because the material captured by gravitation does not allow them to be fed regularly. It is therefore curious that a thin disc surrounding a hungry black hole mimics the much larger discs found in extremely active galaxies.

This disk of material surrounding the black hole is of particular interest and offers a unique opportunity to test the theories of relativity of Albert Einstein. The disc is so deeply embedded in the intense gravitational field of the black hole that the light of the gas disc is modified, according to these theories, offering astronomers a unique insight into the dynamic processes close to the black hole.

"We have never seen the effects of general and special relativity in visible light with so much clarity," said Marco Chiaberge, member of the AURA team for ESA, STScI and Johns Hopkins Univeristy.

Hubble measured the disc material as swirling around the black hole at more than 10% of the speed of light. At such extreme speeds, the gas seems to lighten as it goes to Earth on one side and attenuates as it goes on. he is moving away from our planet from the other. This effect is known as the relativistic beam. Hubble's observations also show that the gas is buried so deep in a gravitational well that the light is struggling to escape and therefore appears stretched at shorter wavelengths. The mass of the black hole is about 250 million times that of the Sun.

"It's an intriguing look on a disc very close to a black hole, so narrow that the velocities and intensity of gravitational attraction affect the way we see photons of light, "explained Stefano Bianchi, first author of the study degli Studi Roma Tre in Italy.

In order to study the matter that is swirling deep inside this disc, the researchers used the Hubble Space Telescope Imaging Spectrometer Instrument (STIS). This diagnostic tool divides the light of an object into several individual wavelengths to determine the speed, temperature, and other characteristics of the object with very high accuracy. STIS was an integral part of the effective observation of the low-light region around the black hole, thus blocking the bright light of the galaxy.

Astronomers initially chose this galaxy to validate the accepted models for active galaxies of lower luminosity: those with malnourished black holes. These models predict that material disks should form when large amounts of gas are trapped by the gravitational pull force of a black hole, then emitting a lot of light and producing a shiny beacon called quasar.

"The type of record we see is a reduced quasar that we did not expect to exist," Bianchi said. "It's the same type of disc we see in 1000, or even 100,000 times brighter objects." The predictions of current models for very weak active galaxies have clearly failed. "

The team hopes to use Hubble to search for other very compact discs around low-light black holes in similar active galaxies.

The paper of the team will appear in the newspaper the Monthly Notices from the Royal Astronomical Society.