Welsh scientists help to unlock secrets of space
Scientists from Wales have contributed to a landmark discovery as colliding stars unlock secrets of the universe.
For the first time scientists have observed gravitational waves and light coming from two neutron stars colliding in a nearby galaxy.
It has enabled scientists to use gravitational waves to measure the expansion rate of the universe, Cardiff University said.
The detection marks the first time that a cosmic event has been viewed in both gravitational waves and light.
The gravitational wave signal was emitted from the collision of two neutron stars 130 million light-years from Earth.
The objects, both 12 miles in diameter, had a mass about half a million times that of the Earth and were orbiting around 200 miles from each other before colliding.
Neutron stars are the smallest, densest stars known to exist and are formed when massive stars explode in supernovas.
These objects are so dense that just a teaspoon of neutron star material would have a mass of about a billion tons.
As the two neutron stars drifted closer together they stretched and distorted space-time giving off energy in the form of powerful gravitational waves – tiny ripples in spacetime – before smashing into each other.
The gravitational waves were detectable for about 100 seconds.
The landmark discovery was made thanks to the significant contribution of Cardiff University scientists who form part of an international collaboration known as the Laser Interferometer Gravitational-Wave Observatory (LIGO) which operate detectors in Washington and Louisiana and observed the signals.
The discovery was also made with the help of the Europe-based Virgo detector and around 70 ground and space-based observatories.
“This discovery ushers in a new era of astronomy where gravitational wave networks and traditional lightbased astronomy will work hand-inhand to uncover some of the universe’s most prized secrets,” Cardiff University said in a statement.
“For the past decade, the Gravitational Physics Group at Cardiff University has laid the foundations for how we go about detecting gravitational waves and have developed novel algorithms and software that have now become standard search tools for detecting the elusive signals.”
When the neutron stars collided a flash of light in the form of gamma rays was emitted and seen by satellites orbiting the Earth about two seconds after the gravitational waves.
In the days following the collision other forms of light such as X-ray, ultraviolet, optical, infrared and radio waves were detected on earth by dozen of teams of astronomers around the world.
Dr Francesco Pannarale, from Cardiff University’s School of Physics and Astronomy, who led one of the analyses on the discovery, said: “This discovery was everything I always hoped for, packed into a single event. “All this rich information came pouring in and we learnt an awful lot.
“My favourite thing is that we confirmed that colliding neutron stars power short gamma-ray bursts, solving one of the greatest mysteries in present day high-energy astrophysics.
“What is exciting is that we know that we will be able to see similar events to this one in the future, allowing us to learn even more about neutron stars, such as the behaviour of matter in their super-dense cores.”
Professor B S Sathyaprakash, also of the School of Physics and Astronomy, said: “The first discovery of gravitational waves took weeks before we could confirm it, but this event was truly a ‘eureka’ moment. “The 12 hours that followed are inarguably the most exciting hours of my scientific life. This event marks a turning point in observational astronomy and will lead to a treasure trove of scientific results.”
One consequence of the detection was that it enabled scientists to use gravitational waves to measure the expansion rate of the universe, known as the “Hubble constant”. This was something that Cardiff University’s Professor Bernard Schutz first predicted would be possible more than more than over 30 years ago.