Final Report Summary - GRAWITON (Gravitational Wave Initial Training Network) Fortune favors the brave. We can use this as a slogan for the GraWIToN project. In fact, GraWIToN was proposed when the gravitational wave research was a topic limited to a small sector of the research in physics, almost not recognised by a large fraction of the astronomer’s community. However, the proposers of the GraWIToN project had clear in mind the enormous potential of the research in gravitational waves, its impact on the future of the observation of the Universe and, mainly, the extreme need to train a future generation of scientists that could play a role in the grown of this sector.The GraWIToN project coincided with the most exciting period in the history of the Astrophysics. In about two years, three crucial discoveries have determined a revolution in the way we are observing the Universe and the GraWIToN ESRs have fully participated to this epochal change: • GW150914: The two LIGO detectors detected for the first time the passage of the gravitational wave emitted by the coalescence of two black holes. The detection occurred on the 14th of September 2015, but the announcement was given by the LIGO and Virgo collaborations on the 11th of February 2016, after an attentive and detailed analysis of the data. It was the full confirmation of the Einstein’s prediction of GW, the birth of the experimental physics of the gravitation in strong field and of the astrophysics of stellar mass black holes.• GW170814: The first detection of GW emitted by the coalescence of black holes, on the 14th of August 2017, in a network of 3 detectors. Both the LIGO detectors and the Virgo detector registered the passage of the gravitational wave localizing the source of the signal within an area of 60 deg2. This detection, thanks to the localization of the source, marks the birth of the gravitational wave astronomy and astrophysics. Furthermore, thanks to the information of the three detectors was possible to evaluate the polarizations of the GW. This discovery was announced by the Virgo and LIGO collaborations during the Science G7 in Turin (September 2017).• GW170817: The first detection of the GW emitted by the coalescence of two Neutron Stars, on the 17th of August 2017. The network of the LIGO and Virgo detectors localized the signal within an area of about 28 deg2. Almost simultaneously the two satellites, Fermi and Integral, detected a gamma ray burst with compatible localization. About 70 detectors and telescopes in the following days, weeks and months observed the source within all the wavelengths of the electromagnetic spectrum, discovering, for the first time, the synthesis of heavy elements like gold and platinum. This discovery represented the solution of the gamma-ray burst enigma, the demonstration of the kilonova role in the synthesis of the heavy elements and, mainly, the beginning of the multi-messenger astronomy and astrophysics era.That incredible period has been completed by the announce of the Nobel prize to three brilliant scientists of the LIGO-Virgo collaboration: R. Weiss, B. Barish, K. Thorne. GraWIToN ESRs have been completely embedded in the activities of LIGO and Virgo, contributing to the analysis that resulted into the detection and to the development or commissioning of the detectors and playing a role in the dissemination of the results. At the same time, they had to attend to an intense programme of six network schools (http://www.grawiton-gw.eu/index.php/network-schools) being trained in GW physics and astronomy, instrument technology, data analysis methods, management of scientific projects both in public and private sector and in science communication. The research activity of the ESRs has been of extreme interest for the development and the results of the GW detectors. For example, the PhD thesis of ESR1 (Matthieu Gosselin) has been a first step in the investigation of the possibility to realise an all-fibred system to inject high power laser light in a GW detector. The activity of ESR9 (Marina Trad Nery) showed an innovative way to realise power stabilization systems for the injected laser light. Between the data analysis oriented thesis, Serena Vinciguerra (ESR13) demonstrated an innovative way to generate GW signal templates in frequency domain.Project Website: http://www.grawiton-gw.eu/.
