Candidate Microlensing Brown Dwarfs in Binary Lens Systems from the 2023--2025 Observing Seasons
Cheongho Han, Andrzej Udalski, Ian A. Bond, Chung-Uk Lee, Michael D. Albrow + 60 more
TLDR
This paper identifies ten candidate brown dwarf companions in binary microlensing systems from 2023-2025 observations.
Key contributions
- Analyzed ten binary-lens microlensing events from 2023-2025 to find brown dwarf candidates.
- Performed detailed light curve modeling, including finite-source effects and angular Einstein radii.
- Determined lens masses and distances for one event via microlens parallax, others via Bayesian analysis.
- All systems show median companion masses in the brown-dwarf regime, two are double brown-dwarf binaries.
Why it matters
This research demonstrates the effectiveness of high-cadence microlensing surveys in detecting brown dwarf companions. It expands our understanding of these faint objects, including distant systems, beyond what traditional flux-limited methods can achieve.
Original Abstract
We present detailed light-curve analyses of ten binary-lens microlensing events observed during the 2023--2025 seasons and selected as candidates for hosting brown-dwarf companions. The sample includes OGLE-2023-BLG-0249, KMT-2023-BLG-1246, OGLE-2023-BLG-0079, KMT-2024-BLG-0072, KMT-2024-BLG-0897, KMT-2024-BLG-1876, KMT-2024-BLG-2379, KMT-2025-BLG-0922, KMT-2025-BLG-1056, and KMT-2025-BLG-2427. For each event, we carry out modeling of the light curve, explore relevant degeneracies, and, when finite-source effects are present, determine the angular Einstein radius. For OGLE-2023-BLG-0249, we additionally measure the microlens parallax, which allows a direct determination of the lens masses and distance. For the remaining events, we estimate the physical lens properties via Bayesian analyses incorporating Galactic priors. The resulting posteriors show that the lens companions in all systems have median masses in the brown-dwarf regime, and the lenses of two events (KMT-2025-BLG-0922 and KMT-2025-BLG-1056) are consistent with binaries in which both lens components fall within the brown-dwarf mass range. Spanning a wide range of projected separations and distances, these detections illustrate the power of high-cadence microlensing surveys to build a census of brown-dwarf companions, including faint and distant systems beyond the reach of flux-limited methods.
📬 Weekly AI Paper Digest
Get the top 10 AI/ML arXiv papers from the week — summarized, scored, and delivered to your inbox every Monday.