First cosmic event observed in both gravitational waves and light

Astronomers from different collaborations announced on Monday 16 October the detection of two colliding neutron stars by the gravitational-wave observatories LIGO and Virgo and also by 70 other, more traditional, electromagnetic-wave observatories. This is the first time scientists have detected gravitational waves in addition to light from the same cosmic event, opening a new window in observational astronomy, the ‘multi-messenger’ astronomy.
After the signal being detected by LIGO detectors in USA and VIRGO in Italy, the position of the event could be precisely triangulated and scientists could locate it in a relatively small patch in the southern sky. Fermi Observatory was able to provide a localization that was later confirmed and greatly refined with the coordinates provided by the LIGO-Virgo detection. With these coordinates some 70 ground- and space-based observatories could point their telescopes to the event and perform follow-up observations in all the range of the electromagnetic spectrum.
The observed event was the merging of two neutron stars located at the relatively close distance of about 130 million light-years from Earth. 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 2 seconds after the gravitational waves. In the days and weeks following the smashup, other forms of or electromagnetic radiation -- including X-ray, ultraviolet, optical, infrared and radio waves -- were detected.



Monday, 16 October, 2017