Microlensing brown-dwarf companions in binaries detected during the 2022 and 2023 seasons

TL;DR

This study identifies six new brown-dwarf companions in binary systems through microlensing events detected by KMTNet during 2022-2023, expanding the sample of known brown dwarf binaries.

Contribution

It presents a homogeneous analysis method to detect brown-dwarf companions in binary systems from microlensing data, including six newly identified candidates.

Findings

Six new brown-dwarf candidates identified

Median companion mass ranges from 0.02 to 0.05 solar masses

Primary lens masses range from 0.11 to 0.68 solar masses

Abstract

Building on previous works to construct a homogeneous sample of brown dwarfs in binary systems, we investigate microlensing events detected by the Korea Microlensing Telescope Network (KMTNet) survey during the 2022 and 2023 seasons. Given the difficulty in distinguishing brown-dwarf events from those produced by binary lenses with nearly equal-mass components, we analyze all lensing events detected during the seasons that exhibit anomalies characteristic of binary-lens systems. Using the same criteria consistently applied in previous studies, we identify six additional brown dwarf candidates through the analysis of lensing events KMT-2022-BLG-0412, KMT-2022-BLG-2286, KMT-2023-BLG-0201, KMT-2023-BLG-0601, KMT-2023-BLG-1684, and KMT-2023-BLG-1743. An examination of the mass posteriors shows that the median mass of the lens companions ranges from 0.02 $M_\odot$ to 0.05 $M_\odot$, indicating that these companions fall within the brown-dwarf mass range. The mass of the primary lenses ranges from 0.11 $M_\odot$ to 0.68 $M_\odot$, indicating that they are low-mass stars with substantially lower masses compared to the Sun.