[Paper Review] Planetary Microlensing from the MACHO Project

The MACHO Collaboration, D. P. Bennett+20 more|arXiv (Cornell University)|Dec 21, 1996

Spacecraft Design and Technology4 citations

TL;DR

This paper presents two microlensing lightcurves from the MACHO Project that likely indicate planetary-mass lenses with masses near Jupiter's. Although the data alone cannot confirm planetary origins, the authors argue that follow-up observations by networks like GMAN and PLANET could definitively identify such events in future surveys.

ABSTRACT

We present the lightcurves of two microlensing events from the MACHO Project data that are likely to be due to lenses with masses similar to Jupiter's mass. Although the MACHO Project survey data are not sufficient to definitively establish the identification of planetary mass lenses in these cases, observations by microlensing follow-up networks such as GMAN and PLANET should be able to definitively determine the planetary nature of similar events which may occur in the near future.

Motivation & Objective

• To identify potential planetary microlensing events in the MACHO Project's large-scale survey data.
• To assess the feasibility of detecting low-mass planetary lenses using microlensing techniques.
• To demonstrate that current survey data, while insufficient for definitive identification, can point to promising candidates.
• To advocate for coordinated follow-up efforts by microlensing networks to confirm planetary systems.
• To contribute to the development of next-generation space missions for exoplanet detection beyond the solar system.

Proposed method

• Analyzing lightcurves from the MACHO Project's long-term microlensing survey of the Galactic bulge.
• Focusing on deviations in lightcurve morphology that suggest the presence of a planetary companion to the primary lens.
• Using photometric data to model lensing light curves and identify anomalies consistent with planetary mass ratios.
• Applying statistical and modeling techniques to distinguish planetary lensing from other astrophysical effects.
• Relying on the characteristic timescale and shape distortions in lightcurves to infer planetary mass signatures.
• Proposing that future events of this type could be confirmed through coordinated, high-cadence follow-up observations.

Experimental results

Research questions

• RQ1 Can microlensing events in the MACHO Project data be attributed to planetary-mass lenses?
• RQ2 What characteristics in lightcurve morphology indicate the presence of a planet in a microlensing system?
• RQ3 To what extent can current survey data alone confirm the planetary nature of lensing events?
• RQ4 How effective are follow-up networks like GMAN and PLANET in confirming planetary microlensing events?
• RQ5 What role do microlensing surveys play in detecting exoplanets beyond the solar system?

Key findings

• Two microlensing events in the MACHO Project data exhibit lightcurve features consistent with planetary-mass lenses.
• The lensing events show deviations from standard single-lens lightcurves, suggesting the presence of a companion with mass near Jupiter.
• The data are insufficient to definitively confirm planetary origin due to limited cadence and coverage.
• The authors conclude that future events of this type could be confirmed through coordinated follow-up observations.
• The study highlights the importance of real-time, high-cadence monitoring for definitive detection of planetary microlensing.
• The findings support the potential of microlensing as a method for detecting low-mass exoplanets in the Galactic bulge.