Scientists have just observed a crash between two neutron stars

On April 25, scientists were able to observe something spectacular with the observation of a recently reopened laser interferometer laser interferometer (LIGO): a ripple in space-time suggesting a collision between two incredibly dense neutron stars.

The interesting part: the collision probably took place 500 million years ago.

The LIGO, alongside the European Virgo detector, recorded the gravitational waves after it reopened in April. They were closed for upgrades. Scientists hope that other observations like this one will be formulated in the near future.

But perhaps the most important discovery is to come. On April 26, the day after the LIGO observed the collision, another candidate source added a dramatic wave to the situation: a potential collision between a neutron star and a black hole.

If confirmed, this will be the first time that scientists record such a collision.

"The universe keeps us on our guard," said Patrick Brady, a professor of physics at the University of Wisconsin-Milwaukee.

The only problem: the signal of this collision was weak, which complicates things.

"It's like listening to someone whispering a word in a busy cafe," says Brady, "it can be hard to understand the word or even to be sure that the person whispers at all. to come to a conclusion about this candidate. "

The possible black hole / neutron star collision would have occurred 1.2 billion light years away. LIGO-Virgo has three separate facilities and the event was spotted by the three, which allowed scientists to locate – up to 3% of the total sky – the place where the l? event took place.

As for the other collision of neutron stars, it proved a little more delicate. Only two of the three installations recorded this event, which means that astronomers will have to scan 25% of the sky to find the source. Good luck with that.

"The search for explosive counterparts of the gravitational wave signal is difficult because of the amount of sky to cover and the expected rapid changes in brightness," Brady said. "The number of neutron star fusion candidates discovered with LIGO and Virgo will provide more opportunities to search for explosions over the next year."

Since it was re-lit, LIGO, associated with Virgo, has also been highlighted by three collisions in black holes. This month has been busy.