2018AJ....155..263S

We report on the analysis of a microlensing event, OGLE-2014-BLG-1722, that showed two distinct short-term anomalies. The best-fit model to the observed light curves shows that the two anomalies are explained with two planetary mass ratio companions to the primary lens. Although a binary-source model is also able to explain the second anomaly, it is marginally ruled out by 3.1σ. The two-planet model indicates that the first anomaly was caused by planet "b" with a mass ratio of q=(4.5_–0.6^+0.7)×10^–4 and projected separation in units of the Einstein radius, s = 0.753 ± 0.004. The second anomaly reveals planet "c" with a mass ratio of q₂=(7.0_–1.7^+2.3)×10^–4 with Δχ² ∼ 170 compared to the single-planet model. Its separation has two degenerated solutions: the separation of planet c is s₂ = 0.84 ± 0.03 and 1.37 ± 0.04 for the close and wide models, respectively. Unfortunately, this event does not show clear finite-source and microlensing parallax effects; thus, we estimated the physical parameters of the lens system from Bayesian analysis. This gives the masses of planets b and c as m_b=56_–33⁺⁵¹ and m_c=85_–51⁺⁸⁶M_⊕, respectively, and they orbit a late-type star with a mass of M_host=0.40_–0.24^+0.36M_☉ located at D_L=6.4_–1.8^+1.3kpc from us. The projected distances between the host and planets are r_⊥,b_=1.5±0.6au for planet b and r_⊥,c_=1.7-0.6_^+0.7au and r_⊥,c_=2.7-1.0_^+1.1au for the close and wide models of planet c. If the two-planet model is true, then this is the third multiple-planet system detected using the microlensing method and the first multiple-planet system detected in low-magnification events, which are dominant in the microlensing survey data. The occurrence rate of multiple cold gas giant systems is estimated using the two such detections and a simple extrapolation of the survey sensitivity of the 6 yr MOA microlensing survey combined with the 4 yr µFUN detection efficiency. It is estimated that 6% ± 2% of stars host two cold giant planets.