Exoplanet Detection Through Extremely Weak Central Perturbation Microlensing by Ground Based Telescopes

DETECTION OF PLANETS IN EXTREMELY WEAK CENTRAL PERTURBATION MICROLENSING EVENTS VIA NEXT-GENERATION GROUND-BASED SURVEYS

Authors:

Chung et al

Abstract:

Even though the recently discovered high-magnification event MOA-2010-BLG-311 had complete coverage over its peak, confident planet detection did not happen due to extremely weak central perturbations (EWCPs, fractional deviations of lsim 2%). For confident detection of planets in EWCP events, it is necessary to have both high cadence monitoring and high photometric accuracy better than those of current follow-up observation systems. The next-generation ground-based observation project, Korea Microlensing Telescope Network (KMTNet), satisfies these conditions. We estimate the probability of occurrence of EWCP events with fractional deviations of ≤2% in high-magnification events and the efficiency of detecting planets in the EWCP events using the KMTNet. From this study, we find that the EWCP events occur with a frequency of >50% in the case of lsim 100 M E planets with separations of 0.2 AU lsim d lsim 20 AU. We find that for main-sequence and sub-giant source stars, gsim 1 M E planets in EWCP events with deviations ≤2% can be detected with frequency less than 50% in a certain range that changes with the planet mass. However, it is difficult to detect planets in EWCP events of bright stars like giant stars because it is easy for KMTNet to be saturated around the peak of the events because of its constant exposure time. EWCP events are caused by close, intermediate, and wide planetary systems with low-mass planets and close and wide planetary systems with massive planets. Therefore, we expect that a much greater variety of planetary systems than those already detected, which are mostly intermediate planetary systems, regardless of the planet mass, will be significantly detected in the near future.