Scientists have long thought that matter sucked by black holes builds up around them, forming a donut-like structure. Findings of a new study however, challenge this idea.
Rings Of Gas Around Black Holes Are Not Rigid Donut-like Structures
Computer simulations and observations from the ALMA observatory in Chile's Atacama Desert have revealed that the rings of gas that surround active supermassive black holes are not simple donut shapes.
Astronomers instead found that the gas expelled from the center of black holes interacts with the infalling gas and create a dynamic circulation pattern that resembles water fountains.
Takuma Izumi, from the National Astronomical Observatory of Japan (NAOJ), and colleagues used ALMA to observe a supermassive black hole in the Circinus Galaxy, which is about 14 million light-years away from Earth. They also used the supercomputer Cray XC30 ATERUI operated by NAOJ to simulate gas falling toward a black hole.
After comparing the observations from ALMA and the computer simulations, the researchers found that the presumptive donut shape of black holes is not actually a rigid structure, but a complex collection of highly dynamic gaseous components.
"Through comparisons with our model predictions based on the radiation-driven fountain scheme, we indicate that atomic outflows are the driver of the geometrical thickness of the atomic disk," Izumi and colleagues wrote in their study, which was published in The Astrophysical Journal on Oct. 30.
Resembles Water Fountains
When cold molecular gas falls toward the black hole, it forms a disk near the plane of rotation. The gas is then heated as it approaches the black hole causing the molecules to break down into atoms and ions.
Instead of being absorbed by the black holes, some of the atoms are expelled above and below the disk. The hot atomic gas also falls back onto the disk to create a three dimensional structure, which circulate continuously similar to a water fountain found in a city park.
"Previous theoretical models set a priori assumptions of rigid donuts," study researcher Keiichi Wada, from the Kagoshima University in Japan, who lead the simulation study said.
"Rather than starting from assumptions, our simulation started from the physical equations and showed for the first time that the gas circulation naturally forms a donut."
