Abstract
Abstract We report the discovery of a sub-Jovian-mass planet, OGLE-2014-BLG-0319Lb. The characteristics of this planet will be added into a future extended statistical analysis of the Microlensing Observations in Astrophysics (MOA) collaboration. The planetary anomaly of the light curve is characterized by MOA and OGLE survey observations and results in three degenerate models with different planetary-mass ratios of q = (10.3, 6.6, 4.5) × 10−4. We find that the last two models require unreasonably small lens-source relative proper motions of μ rel ∼ 1 mas yr−1. Considering Galactic prior probabilities, we rule out these two models from the final result. We conduct a Bayesian analysis to estimate physical properties of the lens system using a Galactic model and find that the lens system is composed of a 0.49 − 0.27 + 0.35 M Jup sub-Jovian planet orbiting a 0.47 − 0.25 + 0.33 M ⊙ M dwarf near the Galactic Bulge. This analysis demonstrates that Galactic priors are useful to resolve this type of model degeneracy. This is important for estimating the mass-ratio function statistically. However, this method would be unlikely successful in shorter timescale events, which are mostly due to low-mass objects, like brown dwarfs or free-floating planets. Therefore, careful treatment is needed for estimating the mass-ratio function of the companions around such low-mass hosts, which only the microlensing can probe.
Highlights
To date, more than 4000 exoplanets have been discovered (Akeson et al 2013), revealing the universality and the diversity of planetary systems
The most recent statistical analysis using the largest sample of microlensing planets was conducted by Suzuki et al (2016), who studied six years of survey data from the second phase of the Microlensing Observations in Astrophysics (MOA-II; Bond et al 2001; Sumi et al 2003) collaboration, including 23 planets discovered from 1474 microlensing events in 2007–2012
They find that the planet-frequency function in the power law describing planet/host mass ratio q has a break around q ∼ 2 × 10−4, which implies Neptune-mass-ratio planets are the most abundant type of planet beyond the snow line
Summary
More than 4000 exoplanets have been discovered (Akeson et al 2013), revealing the universality and the diversity of planetary systems. The most recent statistical analysis using the largest sample of microlensing planets was conducted by Suzuki et al (2016), who studied six years of survey data from the second phase of the Microlensing Observations in Astrophysics (MOA-II; Bond et al 2001; Sumi et al 2003) collaboration, including 23 planets discovered from 1474 microlensing events in 2007–2012 They find that the planet-frequency function in the power law describing planet/host mass ratio q has a break around q ∼ 2 × 10−4, which implies Neptune-mass-ratio planets are the most abundant type of planet beyond the snow line.
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