Scientists have detected waves from a black hole swallowing a neutron star

Artistic representation of a black hole about to swallow a neutron star.Carl Knox, OzGrav Center of Excellence ARC

Nearly a billion years ago, a black hole seems to have devoured a dead star – "like Pac-Man," according to Susan Scott, a physicist at the Australian National University.

The Scott team believes that the spatio-temporal ripples of this event, also called gravitational waves, come to reach the Earth. Albert Einstein was the first to theorize such disturbances by predicting in 1915 that the acceleration of massive objects, such as neutron stars or black holes, would create "waves" in the tissue of the planet. Space and time. However, the first gravitational wave observations did not occur until 2015, 100 years later.

On August 14th, in the United States and Italy, gravitational wave detectors captured new gravitational waves crossing the Earth.

Further research is still needed to confirm the results, but the researchers say that it is highly likely that the signals come from the collision between a black hole and a neutron star – the super dense remnant of a star . This would be the third event that scientists have detected using gravitational waves. In 2015, the researchers detected the collision of the waves of two black holes and, in 2017, observed the fusion of two neutron stars.

A collision between a black hole and a neutron star would complete the trinity of collisions on the wish list, Scott said.

Ripples in space-time indicate violent events

When two black holes collide, they release huge amounts of energy in the form of gravitational waves of a duration of a fraction of a second that can be "heard" in all the universe, if you have the proper instruments.NASA GoddardEinstein did not think that gravitational waves would ever be detected – they seemed too weak to be picked up by all the noises and vibrations of the Earth. For 100 years, he seemed to be right.

But scientists finally managed to detect these ripples with the aid of gravitational wave gravitational observatory (LIGO) in Washington and his sister machine called Virgo in Italy.

In 2015, LIGO detected the first gravitational waves, coming from the collision of two black holes at a distance of 1.3 billion light-years. This discovery confirmed Einstein's theory of general relativity. Then, in 2017, LIGO and Virgo together identified the fusion waves of two neutron stars.

The LIGO L-shaped observatory in Hanford, Washington State.LIGO / NSF Laboratory

To confirm that it's a good third discovery of gravitational waves, telescopes around the world are looking for X-rays or ultraviolet rays in the sky, as the reported National Geographic. If the neutron star survived the collision long enough before the black hole had destroyed it, the dead star could have emitted a light allowing scientists to check the results.

Black holes, however, have a gravitational pulling force such that even light can not escape.

Scientists studying gravitational waves, however, must be prepared for deception, as LIGO and Virgo can trigger false alarms (cases in which detectors simply pick up the sound of the Earth).

A worker inspects quartz fibers that suspend a mirror inside the gravitational wave observatory of the Virgin.EGO / Virgo / Perciballi Collaboration

A potential black hole-neutron collision detected in April, for example, was most likely a false alarm. A signal from this volume has a one in seven chance of being a noise from the Earth. Statistically, LIGO and Virgo could capture this type of false signal every 20 months.

But it is much less likely that LIGO and Virgo will detect a false signal as powerful as the one they detected this month. The researchers calculated what type of error should occurs only once in a period of time greater than the age of the universe, reported National Geographic.

"This is something that is much more exciting," Christopher Berry, a physicist at Northwestern University and LIGO researcher, told National Geographic. "It's much more likely to find a real one, which means it's worth investing more time and effort."

A very light black hole?

A supercomputer simulation shows one of the most violent events in the universe: a pair of neutron stars colliding, merging and forming a black hole. A neutron star is the compressed nucleus that remains when a star born with between eight and thirty times the mass of the sun explodes in the form of a supernova. Neutron stars pack about 1.5 times the mass of the sun into a 12-mile ball.NASA Goddard

Scientists also analyze the data to confirm the exact size of the colliding objects.

Scott said that these results, while they were different from the expected results, could steer the team in another direction: "There is a tiny but intriguing possibility that the object swallowed is a very black hole. light, much lighter than any other black hole in the universe., "she says.

If the smallest object swallowed turned out to be a black hole, it would still be a groundbreaking discovery, as this type of black hole is considered physically impossible. This would open a whole new realm of little black holes to study.

"It would be a really impressive consolation prize," Scott said.