Black hole packed an apparently impossible amount of matter into an almost infinitely small space. This provides black holes with such unimaginably powerful gravitational fields nothing – even light – can escape. And as if black holes were not already mysterious enough, NASA astronomers using the orbiting Hubble Space Telescope have spotted an unexpectedly thin disk of material furiously whirling around a supermassive black hole at the heart of a spiral galaxy 130 million light-years away. The quandary is that the disk should not exist, based on current astronomical theories.
This unexpected presence of a disk so close to a black hole offers a unique opportunity for NASA to test Albert Einstein’s theories of relativity.
We cannot understand the data unless we include the theories of relativity
Professor Stefano Bianchi
General relativity describes gravity as the curvature of space and special relativity describes the relationship between time and space.
The European Space Agency’s member of the team that conducted the Hubble study, said: “We’ve never seen the effects of both general and special relativity in visible light with this much clarity.”
Professor Stefano Bianchi of Università degli Studi Roma Tre, a fellow author, added: “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.
“We cannot understand the data unless we include the theories of relativity.”
Black holes in certain types of galaxies like NGC 3147 are malnourished because there is not enough gravitationally captured material to feed them regularly.
Consequently the in-falling material puffs-up, rather than flattening-out.
It is therefore highly surprisingly to find a thin disk encircling a starving black hole in NGC 3147 that mimics much more powerful disks found in extremely active galaxies with engorged, monster black holes.
Professor Ari Laor of the Technion-Israel Institute of Technology, explained: “We thought this was the best candidate to confirm that below certain luminosities, the accretion disk doesn’t exist anymore.
“What we saw was something completely unexpected. We found gas in motion producing features we can explain only as being produced by material rotating in a thin disk very close to the black hole.”
The disk is so deeply embedded in the black hole’s intense gravitational field that the light from the gas disk is modified, according to Einstein’s theories of relativity, giving astronomers a unique look at the extreme processes close to a black hole.
NASA’s Hubble Space Telescope recorded material hurtling around the black hole at more than 10 percent of the speed of light.
At those 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 side.
Hubble’s observations also show that the gas is so entrenched in the gravitational well the light is struggling to climb out, and therefore appears stretched to redder wavelengths.
The black hole’s mass is equivalent to 250 million of our Suns.
The researchers used Hubble’s Space Telescope Imaging Spectrograph (STIS) to observe matter swirling deep inside the disk.
Spectrograph are diagnostic tools that divides light from an object into its many individual wavelengths to determine its speed, temperature, and other characteristics at a very high precision.
NASA needed STIS’s sharp resolution to isolate the faint light from the black-hole region and block out contaminating starlight.
The ESA’s Marco Chiaberge added: “Without Hubble, we wouldn’t have been able to see this because the black-hole region has a low luminosity.
“The luminosities of the stars in the galaxy outshine anything in the nucleus.
So if you observe it from the ground, you’re dominated by the brightness of the stars, which drowns the feeble emission from the nucleus.”
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