# On the energetics of a possible relativistic jet associated with the binary neutron star merger candidate S190425z

## TL;DR

This paper investigates the potential relativistic jet associated with the binary neutron star merger candidate S190425z by combining gravitational-wave data and electromagnetic observations, providing insights into jet structure and energetics.

## Contribution

It demonstrates how limited GW and EM data can be integrated to constrain the properties of merger outflows and jet structure.

## Key findings

- Observations are consistent with a relativistic structured jet and a short GRB.
- Posterior bounds on the on-axis isotropic energy of the GRB were obtained.
- Combining GW and EM data can yield valuable insights into merger outflows.

## Abstract

Advanced LIGO and Virgo detectors reported the first binary neutron star merger candidate in the third observing run, S190425z, on 25th April 2019. A weak $\gamma$-ray excess was reported nearly coincidentally by the INTEGRAL satellite which accidentally covered the entire localization region of AdvLIGO/VIRGO. Electromagnetic follow-up in longer wavelengths has not lead to the detection of any associated counterparts. Here we combine the available information from gravitational-wave measurements and upper limits of fluence from \textit{INTEGRAL} to show that the observations are completely consistent with a relativistic Gaussian structured jet and a typical short duration Gamma-Ray Burst (GRB) being produced in the merger. We obtain posterior bounds on the on-axis isotropic equivalent energy of the associated GRB under different prior distributions. This study demonstrates that even limited GW and EM information could be combined to produce valuable insights about outflows from mergers. Future follow-ups may help constrain the jet structure further, especially if there is an orphan afterglow detection associated with the candidate.