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

## TL;DR

This paper proposes that a modified gravity model could explain the Geograv detector signal during SN 1987A, suggesting an abrupt metric change caused by neutrino flux, with implications for current gravitational wave detectors.

## Contribution

It introduces a novel explanation for the SN 1987A signal based on extended scalar-tensor theories of gravity affecting detector responses during stellar collapse.

## Key findings

- The initial neutrino pulse could produce a detectable metric change in modified gravity models.
- The second, broader neutrino pulse's influence is exponentially suppressed in the detector.
- This mechanism explains the observed 1.4s delay between Geograv and LSD signals.

## Abstract

A change in gravity law in some regimes is predicted in the modified gravity models that are actively discussed at present. In this paper, we consider a 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 strong 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 by exiting the detector response at the main 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 1.4s between the Geograv and LSD signals. The consequences of this effect of modified gravity for LIGO/Virgo observations are discussed.