# Detecting Multi-Planetary Systems with Gravitational Microlensing and the Roman Space Telescope

**Authors:** Hossein Fatheddin, Sedighe Sajadian  
**arXiv:** [2305.19099](https://arxiv.org/abs/2305.19099)  
**Date:** 2023-05-30  
**Summary page:** https://www.summarizepaper.com/en/paper/2305.19099v1/

## Key points

- Most stars in the Milky Way Galaxy consist of planetary systems rather than single planets
- Around 860 out of approximately 3,950 planet-hosting stars discovered are known to be multiplanetary systems as of March 2023
- Gravitational microlensing is a valuable tool in astrophysics with various applications
- Previous discoveries of exoplanets have been made through binary microlensing
- This study focuses on the detection of multi-planetary systems hosting two exoplanets using microlensing
- The researchers analyze and model possible triple lens configurations involving one star and two planets during a microlensing event
- They examine different magnifications and caustic areas associated with the second planet by comparing magnification maps of triple and binary models under different settings
- The Nancy Grace Roman Space Telescope has potential for detecting light curves corresponding to such planetary systems
- The telescope will provide more data for triple-lens events and has potential for future observations
- Section 2 discusses the properties of triple lens systems, including their characteristics and lens equation
- Section 3 analyzes magnification maps associated with these systems
- Section 4 investigates the possibility of detecting light curves from multi-planetary systems using the Roman space telescope
- The paper summarizes findings and discusses implications in the last section

## Summary

This paper explores the detection of multi-planetary systems using gravitational microlensing and the Roman Space Telescope. It is suggested that most stars in the Milky Way Galaxy, including the Sun, consist of planetary systems rather than single planets. Out of approximately 3,950 planet-hosting stars discovered so far, around 860 are known to be multiplanetary systems as of March 2023. Gravitational microlensing, which refers to the magnification of light from a source star due to one or more lenses, has proven to be a valuable tool in astrophysics with various applications. Previous discoveries of extrasolar planets (exoplanets) have been made through binary microlensing, where a lens system consists of a star with one planet. In this study, the authors discuss and investigate the detection of multi-planetary systems hosting two exoplanets using microlensing. They analyze and model possible triple lens configurations involving one star and two planets during a microlensing event. The researchers also examine different magnifications and caustic areas associated with the second planet by comparing magnification maps of triple and binary models under different settings. Furthermore, the paper discusses the potential for detecting light curves corresponding to such planetary systems with future implementation of the Nancy Grace Roman Space Telescope and its Galactic Time Domain survey. The authors suggest that this telescope will provide even more data for triple-lens events and highlight its potential for future observations. The properties of triple lens systems are discussed in detail in Section 2, including their characteristics and lens equation. In Section 3, the authors analyze magnification maps associated with these systems. Section 4 investigates the possibility of detecting light curves from multi-planetary systems using the Roman space telescope. Finally, in the last section, they summarize their findings and discuss their implications. Overall, this paper contributes to our understanding of multi-planetary systems through gravitational microlensing techniques and highlights its potential for future observations with advanced telescopes like the Roman Space Telescope.