Indications of an unexpected signal associated with the GW170817 binary neutron star inspiral

TL;DR

This study presents evidence of a potential link between a gravitational wave event and correlated changes in radioactive decay rates, suggesting new physics or particles emitted during neutron star mergers.

Contribution

It provides experimental evidence of a correlation between radionuclide decay rates and GW170817, implying possible emission of particles influencing decay processes.

Findings

Highly correlated decay rates immediately after GW170817

Estimated particle mass less than 16 eV from timing analysis

Stronger correlation observed when including data before the GW signal

Abstract

We report experimental evidence at the 2.5$\sigma$ level for an unexpected signal associated with the GW170817 binary neutron star inspiral. This evidence derives from a laboratory experiment simultaneously measuring the $\beta$-decay rates of Si-32 and Cl-36 in a common detector. Whereas the Si-32 and Cl-36 decay rates show no statistical correlation before or after the inspiral, they are highly correlated ($\sim 95\%$) in the 5 hour time interval immediately following the inspiral. If we interpret this correlation as arising from the influence of particles emitted during the inspiral, then we can estimate the mass $m_{x}$ of these particles from the time delay between the gravity-wave signal and a peak in the $\beta$-decay data. We find for particles of energy 10 MeV, $m_{x}$ $\lesssim$ 16 eV which includes the neutrino mass region $m_{\nu}$ $\lesssim$ 2 eV. The latter is based on existing limits for the masses $m_{i}$ of the three known neutrino flavors. Additionally, we find that the correlation is even stronger if we include data in the 80 minute period before the arrival of the gravity wave signal. Given the large number of radionuclides whose decays are being monitored at any given time, we conjecture that other groups may also be in a position to search for statistically suggestive fluctuations of radionuclide decay rates associated with the GW170817 inspiral, and possibly with other future inspirals.