Gravitational waves shed first light on mergers of neutron stars
This is a major breakthrough in more than one respect. The scientists of the LIGO-Virgo Collaboration (which includes the CNRS) have for the first time observed the gravitational waves emitted by the merger of two neutron stars, rather than of two black holes as in previous cases. In another first, the light emitted from the source of gravitational waves was observed in the following hours, days and weeks, by 70 other groundand space-based observatories. This series of observations marks the birth of multi-messenger1 astronomy, and has produced a wealth of results, including a solution to the mystery of gamma-ray bursts and that of the origin of the heaviest elements (such as lead, gold and platinum), as well as new insights into the properties of neutron stars, and an independent measurement of the rate of expansion of the Universe. These various findings are described in a dozen scientific articles published on 16 October 2017 by a number of researchers from CNRS laboratories (more than 200 for one of the publications), members of the LIGO-Virgo Collaboration, and partner astronomy groups. An unprecedented series of events began at 12:41 (UTC) on 17 August 2017 with the detection of a new type of gravitational wave signal. This time, the signal detected was considerably longer than in the case of black hole mergers (around a hundred seconds as opposed to a fraction of a second), a sign that the two objects that finally coalesced were different from those previously detected.
