KMT-2024-BLG-3237: Another Free-floating Planet Candidate with Angular Einstein Radius Measurement

Le résumé fourni par la source

Abstract Planet-formation theories suggest the presence of free-floating planets (FFPs) that are ejected from their formation sites. While these planets emit very little light, they can be identified through gravitational microlensing. Here, we report the discovery of a FFP candidate in the microlensing event KMT-2024-BLG-3237. The observed light curve exhibits strong finite-source effects characterized by a small amplitude (≲0.9 mag) and a short timescale (≲3 days). The analysis yields an Einstein timescale of t E = 0.54 ± 0.02 days and an angular Einstein radius of θ E = 6.30 ± 0.48 μ as. The measurements make it possible to estimate the lens mass as M ≃ 102 M ⊕ ( π rel / 16 μ as ) − 1 , where π rel is the relative lens-source parallax. Depending on the unknown π rel , the lens could be a Neptune-mass planet ( π rel ≃ 0.1 mas) or a Saturn-mass planet ( π rel ≃ 16 μ as). A Bayesian analysis yields the lens mass M = 67.3 − 42.5 + 103.2 M ⊕ and the lens distance D L = 7.34 − 2.11 + 0.96 kpc . This lens is thirteenth isolated microlens with a measurement of θ E < 10 μ as. We find that additional searches for possible signatures of a lens host do not show significant evidence for the host.

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