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RICHLAND – The LIGO observatory in Hanford, near Richland, may have once again marked scientific history in the first month of its new observational tour.
With two other observatories collaborating on gravitational waves, he probably detected the gravitational waves created by a black hole swallowing a neutron star about 1.2 billion light-years away from Earth.
A neutron star is the smallest and densest star type that exists. A piece of neutron star the size of a teaspoon weighs a billion tons.
Gravitational waves, or ripples in space and time, of black hole collisions have been detected several times since 2015.
And a gravitational wave detection from a collision between two neutron stars, revealing radioactive materials that have decayed radioactively to create gold and platinum, has been detected.
But if they were confirmed, the gravitational waves detected on April 26 would be the first time that a collision between a black hole and a neutron star was observed.
Hanford LIGO, his twin in Louisiana and the Virgo gravitational wave observatory in Italy, have made five possible detections of gravitational waves from violent space collisions since the beginning of their last operation. Collaborative observation as of April 1st.
"The universe keeps us on our guard," said Patrick Brady, spokesperson for the LIGO scientific collaboration.
Black holes and neutron stars
One of the latest discoveries concerned the gravitational waves resulting from the collision of two neutron stars 500 million light-years away from the Earth, which would make it the second observed collision of neutron stars.
The other three possible detections involved gravitational waves resulting from collisions with black holes. If confirmed, they would bring the total detected to 13.
Scientists are less sure of any gravitational waves resulting from the collision between a neutron star and a black hole.
"Unfortunately, the signal is rather weak," said Brady. "It's like listening to someone whispering a word in a busy cafe. It can be difficult to spread the word or even to be sure that the person whispers at all. "
Researchers will need time to reach a conclusion, he said.
Unlike black dots, when neutron stars collide, they send not only gravitational waves, but also light.
Since the detection of the first collision of neutron stars in August 2017, the new field of "multi-messenger" astronomy has been launched. Researchers collected data from observation of gravitational and light wave observations.
In the days and months following the event of August 2017, telescopes capable of detecting different types of light waves across the electromagnetic spectrum could witness the inflamed collision of two stars at neutrons. It has been observed in the form of gamma rays, optical light and radio waves.
Telescopes are still searching
But until now, the light of one or the other of the possible events involving neutron stars during the last observation campaign has proved elusive despite the research done by hundreds of astronomers.
Detection in the three observatories allows scientists to triangulate the data to better determine the source of gravitational waves in the sky. But without LIGO Hanford online April 25, scientists have been able to reduce its position to only about a quarter of the sky.
The weak signal of the possible collision between a neutron star and a black hole was reduced to 3% of the total sky.
Gravitational waves were first detected in human history at the Hanford and Louisiana observatories in September 2015, 100 years after Albert Einstein's theory of general relativity predicted the existence of gravitational waves. .
The National Science Foundation has been working in the detection field for 40 years and LIGO detectors have been running from 2002 to 2010 without detection.
The operations were stopped for five years to make them more sensitive, which allowed the first detection of gravitational waves.
Since the initial launch of Advanced LIGO in 2015, the observatories have been closed twice more to allow incremental improvements.
During the last shutdown, the sensitivity of the LIGO and Virgo detectors was significantly improved for the current operating cycle. They can now detect gravitational waves from a larger part of the universe than before.
The LIGO observation series continues
The improvements seem to have paid off, leading to more detections than weekly the first month.
"We see LIGO-Virgo collaborations realizing their potential by regularly producing discoveries that were once impossible," said France Cordova, director of the National Science Foundation. "The data from these discoveries, and others to follow, will help the scientific community revolutionize our understanding of the invisible universe."
The operation of Hanford LIGO and the other two observatories will continue for 11 months.
For the first time of this operation, information is immediately disseminated on possible detections before their confirmation, a process that can take months.
The information allows astronomers around the world to immediately start searching for any light in the sky associated with events.
The public can also sign up for an application for Apple systems that provides detection notifications.
(c) 2019 Tri-City Herald (Kennewick, Wash.)
Distributed by Tribune Content Agency, LLC.
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