# Prospects of joint detections of neutron star mergers and short-GRBs with Gaussian structured jets

## TL;DR

This paper assesses the likelihood of jointly detecting neutron star mergers and short gamma-ray bursts using Gaussian structured jet models, focusing on detection prospects with current and future gravitational wave detectors.

## Contribution

It introduces a model assuming Gaussian structured jets for all neutron star mergers and evaluates joint detection prospects considering inclination, distance, and detection rates.

## Key findings

- Joint detections are limited at large inclination angles due to jet structure.
- Detection rates are constrained by GW detectability at low inclinations.
- Gamma-ray detectability limits joint detections at higher inclinations.

## Abstract

GW170817 was the first ever joint detection of gravitational waves (GW) from a binary neutron star (BNS) merger with the detections of short $\gamma$-ray burst (SGRB) counterparts. Analysis of the multi-band afterglow observations of over more than a year revealed that the outflow from the merger end-product was consistent with structured relativistic jet models with the core of the jet narrowly collimated to half opening angles $\sim5$ deg. In this work, assuming all the BNS mergers produce Gaussian structured jets with properties as inferred for GW170817, we explore the prospects of joint detections of BNS mergers and prompt $\gamma-$ray emission, expected during the current and upcoming upgrades of LIGO-Virgo-KAGRA detectors. We discuss three specific observational aspects: 1) the distribution of detected binary inclination angles 2) the distance reach and 3) the detection rates. Unlike GW-only detections, the joint detections are greatly restricted at large inclination angles, due to the structure of the jets. We find that at lower inclination angles (say below 20 deg), the distance reach as well as the detection rates of the joint detections are limited by GW detectability while at larger inclinations (say above 20 deg), they are limited by the $\gamma$-ray detectability.