“The idea of a black hole ‘sucking in’ a nearby star sounds like science fiction. But this is exactly what happens in a tidal disruption event,” says Matt Nicholl, a lecturer and Royal Astronomical Society research fellow at the University of Birmingham, UK, about at a new flash of light captured by the ESO’s Very Large Telescope and ESO’s New Technology Telescope that occurred last year close to a supermassive black hole.
When a star is devoured by these spacetime monsters they create a tidal disruption event, hot, bright flares generated in the centers of galaxies as an unlucky star wanders too close to a supermassive black hole and gets shredded in what’s known as “spaghettification” as it’s sucked in by the black hole –in this case creating the closest such flare ever recorded at just over 215 million light-years from Earth.
“Black Holes Infinitesimal Dot”
Supermassive black holes teach us, wrote Princeton’s great quantum physicist, John Archibald Wheeler in his autobiography, Geons, Black Holes & Quantum Foam, “that space can be crumpled like a piece of paper into an infinitesimal dot, that time can be extinguished like a blown-out flame, and that the laws of physics that we regard as ‘sacred,’ as immutable, are anything but.”
Death Throes –A Bright Flare of Energy Released
“When an unlucky star wanders too close to a supermassive black hole in the center of a galaxy, the extreme gravitational pull of the black hole shreds the star into thin streams of material” burst of light, which is often obscured by a curtain of dust and debris, explains Thomas Wevers, an ESO Fellow in Santiago, Chile, who was at the Institute of Astronomy, University of Cambridge, UK, when he conducted the work. As some of the thin strands of stellar material fall into the black hole during this spaghettification process, a bright flare of energy is released, which astronomers can detect.
“We found that, when a black hole devours a star, it can launch a powerful blast of material outwards that obstructs our view,” explains Samantha Oates, also at the University of Birmingham. This happens because the energy released as the black hole eats up stellar material propels the star’s debris outwards.”
Tidal Disruption Observed Over 6 Months
The discovery was possible because of the tidal disruption event the team studied over a 6-month period, AT2019qiz, located in a spiral galaxy in the constellation of Eridanus. As the flare grew in luminosity and then faded away just a short time after the star was ripped apart. “Several sky surveys discovered emission from the new tidal disruption event very quickly after the star was ripped apart,” says Wevers. “We immediately pointed a suite of ground-based and space telescopes in that direction to see how the light was produced.”
Unique ‘Peek Behind the Curtain’
“Because we caught it early, we could actually see the curtain of dust and debris being drawn up as the black hole launched a powerful outflow of material with velocities up to 10,000 km/s,” says Kate Alexander, NASA Einstein Fellow at Northwestern University in the US. “This unique ‘peek behind the curtain’ provided the first opportunity to pinpoint the origin of the obscuring material and follow in real time how it engulfs the black hole.”
Ultraviolet, Optical, X-ray and Radio Light
The prompt and extensive observations in ultraviolet, optical, X-ray and radio light using facilities that included X-shooter and EFOSC2, powerful instruments on ESO’s VLT and ESO’s New Technology Telescope (NTT), which are situated in Chile. revealed, for the first time, a direct connection between the material flowing out from the star and the bright flare emitted as it is devoured by the black hole.
“The observations showed that the star had roughly the same mass as our own Sun, and that it lost about half of that to the monster black hole, which is over a million times more massive,” says Nicholl, lead author of the new study who is also a visiting researcher at the University of Edinburgh.
The team reports that AT2019qiz could even act as a ‘Rosetta stone’ for interpreting future observations of tidal disruption events. ESO’s Extremely Large Telescope (ELT), planned to start operating this decade, will enable researchers to detect increasingly fainter and faster evolving tidal disruption events, to solve further mysteries of black hole physics.
Source: “An outflow powers the optical rise of the nearby, fast-evolving tidal disruption event AT2019qiz” to appear in Monthly Notices of the Royal Astronomical Society (doi: 10.1093/mnras/staa2824).
Image credit top of page: ESO/M. Kornmesser