NWO: first time cosmic event viewed in both gravitational waves and light

Artist’s illustration of two merging neutron stars. The narrow beams represent the gamma-ray burst while the rippling spacetime grid indicates the isotropic gravitational waves that characterize the merger. Swirling clouds of material ejected from the merging stars are a possible source of the light that was seen at lower energies. Credit: National Science Foundation/LIGO/Sonoma State University/A. Simonnet

The Hague, The Netherlands, 18-Oct-2017 — /EuropaWire/ — For the first time, scientists have directly detected gravitational waves — ripples in space and time — in addition to light from the spectacular collision of two neutron stars. This marks the first time that a cosmic event has been viewed in both gravitational waves and light. The discovery was made using the U.S.-based Laser Interferometer Gravitational-Wave Observatory (LIGO); the Europe-based Virgo detector; and some 70 ground- and space-based observatories.

Neutron stars are the smallest, densest stars known to exist and are formed when massive stars explode in supernovas. As these neutron stars spiraled together, they emitted gravitational waves that were detectable for about 100 seconds; when they collided, a flash of light in the form of gamma rays was emitted and seen on Earth about two seconds after the gravitational waves. In the days and weeks following the smashup, other forms of light, or electromagnetic radiation — including X-ray, ultraviolet, optical, infrared, and radio waves — were detected.

The observations have given astronomers an unprecedented opportunity to probe a collision of two neutron stars. For example, observations made by the U.S. Gemini Observatory, the European Very Large Telescope, and NASA’s Hubble Space Telescope reveal signatures of recently synthesized material, including gold and platinum, solving a decades-long mystery of where about half of all elements heavier than iron are produced.

Nikhef director Stan Bentvelsen says the discovery is “incredibly exciting”. “Detecting the merging of neutron stars, first through gravitational waves and immediately afterwards through observations with optical telescopes provides an entirely new picture of these cosmic events. As far as I am concerned, this is the event of the century, which marks a new acquaintance with our universe.”

More information

• Visit the Nikhef website for more details
• Nikhef is a partnership between NWO and five universities
• Read more about ripples in spacetime (article in ExperimentNL, 2016)

SOURCE: The Netherlands Organisation for Scientific Research (NWO)

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• Olivier Morot o.morot@nwo.nl
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• Poppy Savenije p.savenije@nwo.nl
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