The Multi-Messenger Astroparticle Physics: the First Constraint on Light Millicharged Dark Matter via Time-Delay Analysis of GRB GW170817A

The multi-messenger astroparticle physics provides a new approach to probe the new physics beyond the Standard Model. We propose to probe the light dark matter which can interact with electromagnetic interaction. To be concrete, we derive the new constraint on the millicharged dark matter from the multi-messenger observations of GW170817. In the neutron star merger event GW170817, the first detection of a gamma-ray burst (GRB) delayed by approximately 1.7 seconds relative to the gravitational wave emission was observed. Utilizing this delay, we constrain the parameter space of the millicharged dark matter within the large-scale structure of the Universe. For dark matter mass below ${10}^{-15}$ eV, the parameter $\epsilon$ is constrained to be less than ${10}^{-14}$, representing the most stringent limits achieved to date.