Simulations of Triple Microlensing Events I: Detectability of a scaled Sun-Jupiter-Saturn System

TL;DR

This study develops simulation software to assess the detectability of a scaled Sun-Jupiter-Saturn system in triple microlensing events, highlighting detection challenges and the impact of planetary interactions for future space-based surveys.

Contribution

It introduces a simulation framework for triple-lens microlensing systems and analyzes the detectability of a scaled Sun-Jupiter-Saturn analog with upcoming space telescopes.

Findings

Detectability of the scaled Sun-Jupiter-Saturn system is about 1%.

Presence of Jupiter-like planet reduces Saturn detectability by approximately 13%.

Detection efficiency calculations should consider planetary interactions, not treat planets separately.

Abstract

Up to date, only 13 firmly established triple microlensing events have been discovered, so the occurrence rates of microlensing two-planet systems and planets in binary systems are still uncertain. With the upcoming space-based microlensing surveys, hundreds of triple microlensing events will be detected. To provide clues for future observations and statistical analyses, we initiate a project to investigate the detectability of triple-lens systems with different configurations and observational setups. As the first step, in this work we develop the simulation software and investigate the detectability of a scaled Sun-Jupiter-Saturn system with the recently proposed telescope for microlensing observation on the ``Earth 2.0 (ET)'' satellite. With the same $\Delta\chi^2$ thresholds of detecting a single planet and two planets, we find that the detectability of the scaled Sun-Jupiter-Saturn analog is about 1% and the presence of the Jovian planet suppresses the detectability of the Saturn-like planet by $\sim $13% regardless of the adopted detection $\Delta\chi^2$ threshold. This suppression probability could be at the same level as the Poisson noise of future space-based statistical samples of triple-lenses, so it is inappropriate to treat each planet separately during detection efficiency calculations.