The Universe never seen before: Italy in the forefront of the new era of astronomy
For the first time in the history of the observation of the Universe, scientists on the Earth have detected joint signals of gravitational waves and electromagnetic radiations produced by the merger of two neutron stars.
This is an historic event that has revealed important secrets about these cosmic events and the formation of heavy chemical elements found in the Universe – such as gold, lead and platinum – marking the beginning of a new era of observation of the Universe. The discovery marks the beginning of the so-called multi-messenger astronomy, which will expand our way to “look at” and “listen to” the Universe by using different observation instruments directed to a single source.
This discovery is the result of an international joint effort, with Italy in the forefront, which has involved the large gravitational wave detectors LIGO, located in the United States, and VIRGO, in Italy, together with 70 telescopes on the Earth – including VLT (Very Large Telescope) and VST (VLT survey telescope) of the European Southern Observatory (ESO) – and several observatories located in the space, including Integral and Swift with participation of the Italian Space Agency (ASI), Fermi, Chandra, Hubble.
“Italian research played a crucial role and showed to be able to coordinate different fields and different types of instruments, located both on the ground and in the space, being fully entitled to participate in one of the most important networks of global research. – said Roberto Battiston, President of the Italian Space Agency (ASI). – ASI is already committed to reach the next frontier, the development of the large interferometer LISA for the detection of gravitational waves in the space, capable of multiplying by orders of magnitude the sensitivity to this new type of radiations” concluded Battiston.
An unprecedented cosmic “clash”
The cosmic “clash” – happened 130 million light years away, in the direction of the constellation of Hydra – was captured last 17 August by the two LIGO gravitational wave detectors, located in the states of Washington and Louisiana. Then, the signal detected by Italian VIRGO detector allowed scientists to triangulate the cosmic source and precisely locate it in the sky.
At the end of the approaching process, the two stars emitted a flash of light in the form of gamma ray bursts and then merged in a single very dense celestial object (whether it was a neutron star or a black hole is still an open question). The unprecedented location of the source allowed to direct telescopes located all over the world towards that region of the Universe, thus obtaining unique scientific data on the emission of “light” and “sounds” in different wavelengths, including X-rays, ultraviolet rays, visible light, infrared light and radio waves.
“This achievement was possible thanks to the joint effort of thousands of people”, said Fernando Ferroni, President of the National Institute for Nuclear Physics (INFN). “In particular, we at INFN are glad to have greatly contributed to this achievement, and this is the culmination of an ambitious project, VIRGO, started over twenty years ago by visionary and steadfast physicist Adalberto Giazotto” concluded Ferroni.
A “mine” of gold and platinum
Among the most important scientific results, the observation of the cosmic event has provided scientists with the first direct confirmation that collisions between neutrons produce short-term Gamma Ray Bursts, and also provided crucial information about the density of the matter within these celestial bodies. Moreover, the observations have revealed, for the first time, that these cosmic events are responsible for the formation of the heavy chemical elements of the periodic table – such as gold, lead and platinum – which are then “distributed” all over the Universe.
Finally, the data collected led to determining the Hubble constant, which measures the expansion rate of the Universe, and to observe that gravitational waves travel at “approximately” the speed of light, as predicted by Einstein’s Theory of General Relativity. Gravitational and electromagnetic waves generated 130 million light years away have reached the Earth with a difference of 1.7 seconds only, thus showing scientists that the speed of propagation of gravitational waves differs from the speed of light by an infinitesimal.