[ad_1]
Astronomers may have seen for the first time a neutron star being swallowed by a black hole, marked by a wave of gravitational waves waving in the cosmos.
If confirmed, detection by the Ligo twin detectors in the United States and by the Virgo detector in Italy would be the first evidence that black holes and neutron stars can be coupled in binary systems. The observations could also reveal new details about the nature of such spectacular fusions, especially if the neutron star had been torn apart before crossing the black hole threshold or if it was transparently slipping into oblivion.
Patrick Brady, spokesperson for the Ligo collaboration and professor of physics at the University of Wisconsin-Milwaukee, said the signal of the eventual collision, which occurred on April 26, required further analysis before the team was convinced that it was a real event. that a rap in the background noise. "It's like listening to someone whispering a word in a busy cafe, it can be difficult to make it clear or even to be sure that the person whispers at all," he said. "It will take some time to reach a conclusion about this candidate."
He put the chances that the observations are a glitch in the data at 14%.
Ligo and Virgo capture the tiny ripples in the structure of space and time that are sent across the cosmos when two gigantic objects collide.
The possible detection came just a day after the Ligo and Virgo detectors identified a cataclysmic fusion of two neutron stars for the second time only. Since the start of their third observation campaign on April 1, detectors have also spotted three mergers of black holes.
Neutron stars are the smallest and densest known stars. They measure about 12 miles wide and a teaspoon of neutron star material has a mass of about one billion tons. They have a smooth crust of pure neutrons, 10 billion times stronger than steel. These are the collapsed remains of giant stars, after a supernova explosion – even more massive stars form black holes.
When two neutron stars collide, they send not only gravitational waves, but also light. Therefore, if astronomers are able to rotate their optical telescopes to the sky on the right, they can also capture the explosive consequences in the form of light waves.
The location of the possible fusion between a neutron star and a black hole, which would have occurred 1.2 billion light years from Earth, was reduced to about 3% of the total sky – but the area is vast.
"All the astronomers are now chasing a huge part of the sky to see if the light came on at that time," said Professor Alberto Vecchio, director of the University's Institute for Gravitational Wave Astronomy. from Birmingham.
Detecting a radiation flash could reveal crucial details about the size of the objects and the nature of the fusion. Contrary to popular belief, the largest black holes are the least dense and the gravitational force at the edge of these objects is less fierce. A neutron star colliding with a very large black hole could simply disappear from view. "The neutron star would dive and nothing would happen, that's all," said Vecchio.
On the other hand, for a smaller black hole, gravity close to the event horizon would be so fierce that it could shred the neutron star and engulf it in several pieces. "Then you will have this extremely dense material moving at a fraction of the speed of light," said Vecchio, who he says could emit spectacular bursts of radiation that can be spotted by telescopes on Earth.
Since Ligo began observing in 2015, his sensitivity has been significantly increased, allowing him to perform several detections a month. This increases the chances that it detects previously unseen and theoretically predicted exotic objects, such as boson stars or black mini-holes.
"We are opening a new window to the universe and hope it will bring us a whole new perspective on what's out there," Brady said.
[ad_2]
Source link