paper

The frequency of snowline-region planets from four-years of OGLE-MOA-Wise second-generation microlensing

arXiv:1510.04297 · doi:10.1093/mnras/stw191

Abstract

We present a statistical analysis of the first four seasons from a "second-generation" microlensing survey for extrasolar planets, consisting of near-continuous time coverage of 8 deg of the Galactic bulge by the OGLE, MOA, and Wise microlensing surveys. During this period, 224 microlensing events were observed by all three groups. Over 12% of the events showed a deviation from single-lens microlensing, and for 1/3 of those the anomaly is likely caused by a planetary companion. For each of the 224 events we have performed numerical ray-tracing simulations to calculate the detection efficiency of possible companions as a function of companion-to-host mass ratio and separation. Accounting for the detection efficiency, we find that of microlensed stars host a snowline planet. Moreover, we find that Neptunes-mass planets are times more common than Jupiter-mass planets. The companion-to-host mass ratio distribution shows a deficit at , separating the distribution into two companion populations, analogous to the stellar-companion and planet populations, seen in radial-velocity surveys around solar-like stars. Our survey, however, which probes mainly lower-mass stars, suggests a minimum in the distribution in the super-Jupiter mass range, and a relatively high occurrence of brown-dwarf companions.

arXiv comment24 pages, 13 figures, 2 tables. 2016, MNRAS, 457, 4089

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