KMT-2022-BLG-0086: Another binary-lens binary-source microlensing event

Abstract

We present the analysis of a microlensing event KMT-2022-BLG-0086 of which the overall light curve is not described by a binary-lens single-source (2L1S) model, which suggests the existence of an extra lens or an extra source. We found that the event is best explained by the binary-lens binary-source (2L2S) model, but the 2L2S model is only favored over the triple-lens single-source (3L1S) model by $\hat{I}”\ddot{I}{‡}^2\simeq 9$. Although the event has noticeable anomalies around the peak of the light curve, they are not enough covered to constrain the angular Einstein radius $\hat{I}{¸}_{\mathrm{E}}$, thus we only measure the minimum angular Einstein radius $\hat{I}{¸}_{\mathrm{E},\min }$. From the Bayesian analysis, it is found that that the binary lens system is a binary star with masses of $(m_1,m_2)=(0.46_{-0.25}^{+0.35}{M}_{\odot },0.75_{-0.55}^{+0.67}{M}_{\odot })$ at a distance of $D_{\mathrm{L}}=5.87_{-1.79}^{+1.21}$ kpc, while the triple lens system is a brown dwarf or a massive giant planet in a low-mass binary-star system with masses of $(m_1,m_2,m_3)=(0.43_{-0.35}^{+0.41}{M}_{\odot },0.056_{-0.047}^{+0.055}{M}_{\odot },20.84_{-17.04}^{+20.20}{M}_{\mathrm{J}})$ at a distance of $D_{\mathrm{L}}=4.06_{-3.28}^{+1.39}$ kpc, indicating a disk lens system. The 2L2S model yields the relative lens-source proper motion of $\hat{I}{¼}_{\mathrm{rel}}⩾4.6\mathrm{mas}\mathrm{y}{\mathrm{r}}^{-1}$ that is consistent with the Bayesian result, whereas the 3L1S model yields $\hat{I}{¼}_{\mathrm{rel}}⩾18.9\mathrm{mas}\mathrm{y}{\mathrm{r}}^{-1}$, which is more than three times larger than that of a typical disk object of $\sim 6\mathrm{mas}\mathrm{y}{\mathrm{r}}^{-1}$ and thus is not consistent with the Bayesian result. This suggests that the event is likely caused by the binary-lens binary-source model.

13 pages, 10 figures, AJ in press