Prospects of Gravitational Wave Follow-up Through a Wide-field Ultra-violet Satellite: a Dorado Case Study

TL;DR

This study evaluates how a wide-field ultra-violet satellite like Dorado could rapidly follow up gravitational wave detections to distinguish between different physical processes driving early kilonova emission, enhancing multimessenger astronomy.

Contribution

It demonstrates that a Dorado-like UV satellite can effectively differentiate emission components and constrain kilonova parameters up to 160 Mpc, informing future observational strategies.

Findings

Dorado-like satellite can distinguish emission components within hours up to 160 Mpc.

Combining UV and optical data tightens parameter constraints.

UV data alone constrains outer ejecta properties.

Abstract

The detection of gravitational waves from binary neuron star merger GW170817 and electromagnetic counterparts GRB170817 and AT2017gfo kick-started the field of gravitational wave multimessenger astronomy. The optically red to near infra-red emission (`red' component) of AT2017gfo was readily explained as produced by the decay of newly created nuclei produced by rapid neutron capture (a kilonova). However, the ultra-violet to optically blue emission (`blue' component) that was dominant at early times (up to 1.5 days) received no consensus regarding its driving physics. Among many explanations, two leading contenders are kilonova radiation from a lanthanide-poor ejecta component or shock interaction (cocoon emission). In this work, we simulate AT2017gfo-like light curves and perform a Bayesian analysis to study whether an ultra-violet satellite capable of rapid gravitational wave follow-up, could distinguish between physical processes driving the early `blue' component. We find that a Dorado-like ultra-violet satellite, with a 50 sq. deg. field of view and a limiting magnitude (AB) of 20.5 for a 10 minute exposure is able to distinguish radiation components up to at least 160 Mpc if data collection starts within 3.2 or 5.2 hours for two possible AT2017gfo-like light curve scenarios. We also study the degree to which parameters can be constrained with the obtained photometry. We find that, while ultra-violet data alone constrains parameters governing the outer ejecta properties, the combination of both ground-based optical and space-based ultra-violet data allows for tight constraints for all but one parameter of the kilonova model up to 160 Mpc. These results imply that an ultra-violet mission like Dorado would provide unique insights into the early evolution of the post-merger system and its driving emission physics.