Four Cold Super-Jupiters Revealed by Extended and Complex Microlensing Signals

TL;DR

This paper reports the discovery of four super-Jupiter exoplanets through detailed analysis of complex microlensing signals, emphasizing microlensing's ability to detect cold, distant giant planets beyond the snow line.

Contribution

It demonstrates that extended and complex microlensing anomalies can reveal planetary signals, highlighting the importance of systematic reanalysis of survey data for exoplanet detection.

Findings

All four anomalies are caused by planetary companions to low-mass stars.

The planets are super-Jupiters with masses of a few to 10 Jupiter masses.

Planets are located beyond the snow line, in the cold giant planet regime.

Abstract

We present the analysis of four microlensing events, KMT-2020-BLG-0202, KMT-2022-BLG-1551, KMT-2023-BLG-0466, and KMT-2025-BLG-0121, which exhibit extended and complex anomalies in their light curves. These events were identified through a systematic reanalysis of KMTNet data aimed at detecting planetary signals that deviate from the typical short-term anomaly morphology. Detailed modeling indicates that all four anomalies were produced by planetary companions to low-mass stellar hosts. The events have mass ratios of $q \sim (5$--$14)\times10^{-3}$ and Einstein timescales of $t_{\rm E} \sim 20$--$43$ days. Bayesian analyses based on Galactic models show that the companions are super-Jupiters with masses of a few to approximately 10 $M_{\rm J}$, orbiting sub-solar-mass hosts located at distances of $D_{\rm L} \sim 4$--$7$~kpc. All planets lie well beyond the snow line of their hosts, placing them in the regime of cold giant planets. These detections demonstrate that extended and complex microlensing anomalies, which are often challenging to recognize as planetary in origin, can nonetheless contain planetary signals. This work underscores the unique sensitivity of microlensing to cold, massive planets beyond the snow line and highlights the importance of systematic reanalyses of survey data for achieving a more complete and unbiased census of exoplanets in the Galaxy.