Astronomers don’t have to wait much longer for their first glimpse of one of the biggest supermassive black holes collision in the cosmos.
A US collaboration of astronomers has detected two supermassive black holes headed for a collision. Each 800 million times more massive than our sun are about 2.5 billion light-years away from Earth. The two black holes will continue to get closer to each other sending out huge ripples in space-time, also known as gravitational waves, which can be detected back to Earth.
The gravitational waves from the two supermassive black holes are a million times louder than those detected by LIGO. Although we’re not likely to detect their cosmic waves for billions of years, they will help astronomers gain a better understanding of black holes.
“Collisions between enormous galaxies create some of the most extreme environments we know of, and should theoretically culminate in the meeting of two supermassive black holes, so it was incredibly exciting to find such an immensely energetic pair of black holes so close together in our Hubble Space Telescope images,” said Andy Goulding, an associate research scholar in astrophysical sciences at Princeton who is the lead author on a paper appearing July 10 in Astrophysical Journal Letters.
What happens when two Black Holes collide?
Supermassive black holes are usually found at the center of large galaxies, including our own Milky Way. When galaxies merge, the supermassive black holes drift to the center of the newly unified galaxy and begin orbiting one another. Astrophysicists predict this orbit tightens and the black holes merge over time. The get-together produces intense gravitational waves that ripple through the fabric of space and time.
If the black hole merger isn’t detected, it could be because black holes stall at around 1 parsec (roughly 3.2 light-years) apart. This slowdown lasts indefinitely and is known as the final parsec problem.
The biggest promise of the latest discovery is that it would help researchers learn how much time it takes for black holes to merge – or indeed if they merge at all.
But that’s not the end of uncertainties for astronomers. Bigger galaxies have bigger black holes and therefore stronger gravitational waves. But bigger black holes also merge faster, reducing the window during which gravitational waves may be detected.
Successful detection of gravitational waves would give astrophysicists a better understanding of how massive galaxies and black holes evolve.