Researchers from UC Berkeley and the Hebrew University of Jerusalem have shined a light on the mysteries surrounding black holes and their nearby galaxies in a study published in April.
The researchers pieced together how some jets — bright plumes of gas emitted from black holes — might trigger widespread galactic changes as part of a process that has puzzled scientists for decades, according to a campus press release. The study was funded by NASA through the Einstein Postdoctoral Fellowship grant.
“Understanding how black holes produce these jets and whether they’re able to heat up the galaxy … is very important for our understanding of galaxy evolution,” said Alexander Tchekhovskoy, a postdoctoral researcher who led the project.
Black holes — or dense regions of space sometimes weighing “millions or even billions” of tons more than the sun — constantly vacuum materials from their surroundings so even light becomes irretrievable, according to campus astronomy professor Alex Filippenko.
Some gas, however, becomes energized while falling inside the black hole and spews out as jets along a magnetic field, also radiating light. Tchekhovskoy said that, while many jets push beyond their galaxies into space, others break off and fizzle inside — gaining the potential to discourage new star formation and lower the mass of the black hole over the course of millions of years.
The researchers revealed for the first time that instability in the magnetic field used to generate jets — which squeezes a jet against neighboring gas as if between “a rock and a hard place” — determines the course of action the jet takes, depending on the strength of the jet.
Tchekhovskoy said the process was similar to drilling a hole in the wall. Though a weak screw might bend against the wall without piercing it, a rigid screw would penetrate the wall — similar to how a weak jet would break under a magnetic field while a stronger jet would project into space under the same forces.
According to Tchekhovskoy, the researchers generated their findings by simulating black hole jets using 2,000 supercomputers over the course of 500 hours — a process that would take a million hours using a conventional laptop or cellphone.
Filippenko said advances in computer technology over the last 30 years paved the way for the discovery by providing numerical data to confirm long-held conjecture about jets. He added that he was “not surprised” by the qualitative findings of the study.
“I think (the study) is based on fairly well-developed, standard physics that’s now been applied to this interesting type of galaxy,” Filippenko said.
According to campus postdoctoral researcher Ann-Marie Madigan, knowledge about black holes is difficult to obtain because data ranges across several physical disciplines and is difficult to measure numerically.
Madigan noted that the way jets affect their galactic environments is still a “relatively new question” and that shedding light on the process further would involve taking time to formulate “a lot of basic theoretical groundwork.”
Tchekhovskoy said the team plans on researching the effects of black holes — including those of jet emissions — on their corresponding galaxies in the future.