Savchenko, V.V.SavchenkoFerrigno, C.C.FerrignoMEREGHETTI, SandroSandroMEREGHETTINATALUCCI, LORENZOLORENZONATALUCCIBAZZANO, ANGELAANGELABAZZANOBozzo, E.E.BozzoBrandt, S.S.BrandtCourvoisier, T. J. -L.T. J. -L.CourvoisierDiehl, R.R.DiehlHanlon, L.L.Hanlonvon Kienlin, A.A.von KienlinKuulkers, E.E.KuulkersLaurent, P.P.LaurentLebrun, F.F.LebrunRoques, J. P.J. P.RoquesUbertini, P.P.UbertiniWeidenspointner, G.G.Weidenspointner2020-05-122020-05-1220162041-8205http://hdl.handle.net/20.500.12386/24742Using observations of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), we place upper limits on the gamma-ray and hard X-ray prompt emission associated with the gravitational wave event GW150914, which was discovered by the LIGO/Virgo Collaboration. The omnidirectional view of the INTEGRAL/SPI-ACS has allowed us to constrain the fraction of energy emitted in the hard X-ray electromagnetic component for the full high-probability sky region of LIGO triggers. Our upper limits on the hard X-ray fluence at the time of the event range from {F}<SUB>γ </SUB>=2× {10}<SUP>-8</SUP> erg cm<SUP>-2</SUP> to {F}<SUB>γ </SUB>={10}<SUP>-6</SUP> erg cm<SUP>-2</SUP> in the 75 keV-2 MeV energy range for typical spectral models. Our results constrain the ratio of the energy promptly released in gamma-rays in the direction of the observer to the gravitational wave energy E {}<SUB>γ </SUB>/ E {}<SUB>{GW</SUB>}\lt {10}<SUP>-6</SUP>. We discuss the implication of gamma-ray limits for the characteristics of the gravitational wave source, based on the available predictions for prompt electromagnetic emission.STAMPAenArticle10.3847/2041-8205/820/2/L362-s2.0-84963684456000373085300014https://iopscience.iop.org/article/10.3847/2041-8205/820/2/L362016ApJ...820L..36SFIS/05 - ASTRONOMIA E ASTROFISICA