Using the NASA/ESA Hubble Telescope, astronomers have discovered a mysterious black hole disc of material at the center of the spiral galaxy NGC 3147.
Astronomers have observed a mysterious thin disc of material furiously whirling around a supermassive black hole. It lies at the heart of the spiral galaxy NGC 3147 about 130 million light-years away from us.
Based on current theories, the disc shouldn’t even be there. Astronomers were surprised to find the black hole disc in such a low-luminosity active galaxy.
Black holes in galaxies such as NGC 3147 are usually pretty quiet and starving. That’s because there is insufficient material to feed them regularly.
However, this mysterious disc offers a unique opportunity to test Albert Einstein’s theories of relativity.
“We’ve never seen the effects of both general and special relativity in visible light with this much clarity,” said team member Marco Chiaberge of the European Space Agency, and the Space Telescope Science Institute and Johns Hopkins University.
Hubble measured the disc of material to be rotating around the black hole at more than 10% of the speed of light. Because of such extreme speeds, the gas appears to brighten as it travels toward Earth on one side and dims as it speeds away from our planet on the other. Astronomers call this effect the relativistic beaming.
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Hubble also showed that the gas is embedded so deep in a gravitational well that light is struggling to escape, and therefore appears stretched to redder wavelengths. The black hole’s mass is around 250 million times that of the Sun.
“This is an intriguing peek at a disk very close to a black hole, so close that the velocities and the intensity of the gravitational pull are affecting how the photons of light look,” added the study’s first author, Stefano Bianchi of Università degli Studi Roma Tre, in Rome, Italy. “We cannot understand the data unless we include the theories of relativity.”
To study the matter swirling deep inside this disc, the researchers used the Hubble Space Telescope Imaging Spectrograph (STIS) instrument. STIS managed to observe the low-luminosity region around the black hole by blocking out the galaxy’s brilliant light.
The astronomers chose this galaxy to validate accepted models about lower-luminosity active galaxies — galaxies with malnourished black holes. Models predict that an accretion disk forms when the strong gravity of a black hole attracts enough amounts of gas. Therefore, the infalling matter emits lots of light and produces a quasar.
“The type of disc we see is a scaled-down quasar that we did not expect to exist,” Bianchi explained. “It’s the same type of disc we see in objects that are 1000 or even 100 000 times more luminous. The predictions of current models for very faint active galaxies clearly failed.”
The team’s paper will appear online today in the Monthly Notices of the Royal Astronomical Society.