Black Holes ‘Outshine’ All Stars in the Sky, Study Finds

Every high school physics student knows that not even light can escape from a black hole’s gravity. But under the right conditions, spinning black holes can interact with surrounding plasma to create enough energy to outshine all of the stars of the universe.

Now new research by a team including a University of Guelph scientist suggests that paired black holes throw off even stronger paired jets whose energy dwarfs that of the estimated 10,000 billion billion stars in the universe.

The research is discussed in a paper called “Boosting Jet Power in Black Hole Spacetimes” co-authored by Guelph physicist Luis Lehner and researchers from the United States and Canada. The paper was published this week in the Proceedings of the National Academy of Sciences.

The researchers used simulations to model how single and double black hole systems spin and interact with plasma and an ambient magnetic field.

Instead of being sucked into the black hole, plasma skirting the rim of these rotating gravitational behemoths is thrown off as enormous narrow jets of light. Jets might also arise from plasma interactions of a black hole paired with a neutron star.

These events typically occur as gamma ray bursts, quasars and active galactic nuclei billions of light years from Earth. “These energies are incredible,” said Lehner. “They outshine the rest of the universe combined. How can a tiny system put out equal or more energy than the rest of the universe combined?”

Current telescopes can detect these events but not clearly enough to distinguish dual or single jets. Scientists are now building instruments to better detect light or gravitational waves from these systems.

Studying active black holes might help us learn more about how galaxies and stars form and about the most energetic events in our universe.

Scientists believe black holes exist in every galaxy, including one in our Milky Way, although it’s located thousands of light years from our planet.

Compared with those far-distant events in the research team’s model, the Milky Way is a “quiet” galaxy with a slower-spinning black hole. “Our black hole is on the wimpy side,” said Lehner. Scientists don’t know why our galaxy is so much quieter, although they believe it was once more active.

Lehner said a nearby cosmic explosion could fry Earth, but the probability of such an event is low. Scientists predict that the Milky Way will eventually collide with its nearest neighbour galaxy, Andromeda, but not for billions of years. “We don’t have to worry; it’s very much in the future.”

Earlier this year, Lehner was named a Fellow of the American Physical Society. He is cross-appointed to the Perimeter Institute for Theoretical Physics in Waterloo, Ont.

