Possible Explanation of the Geograv Detector Signal during the Explosion of SN 1987A in Modified Gravity Models

A change in the law of attraction in some regimes is predicted in the modified gravity models being actively developed at present. The set of up-to-date observational data leaves a wide range of admissible parameters for the theory. In this paper, we consider the possibility that the signal recorded by the Geograv resonant gravitational-wave detector in 1987 during the explosion of SN 1987A was produced by an abrupt change in the metric during the passage of a powerful neutrino flux through the detector. Such an impact on the detector is possible, in particular, in extended scalar–tensor theories in which the local matter density gradient affects the gravitational force. The first short neutrino pulse emitted at the initial stage of stellar core collapse before the onset of neutrino opacity could exert a major influence on the detector, because it could produce the detector response at the first resonance frequency. In contrast, the influence of the subsequent broad pulse (with a duration of several seconds) in the resonant detector is exponentially suppressed, despite the fact that the second pulse carries an order-of-magnitude more neutrino energy, and it could generate a signal in the LSD neutrino detector. This explains the time delay of 1.4 s between the Geograv and LSD signals. The consequences of this effect of modified gravity for future LIGO/Virgo observations are discussed.