2013MNRAS.431.2975A

A measurement by microlensing of the planetary mass function of planets with masses ranging from 5 M⊕ to 10MJ and orbital radii from 0.5 to 10 au was reported recently. A strategy for extending the mass range down to (1-3) M⊕ is proposed here. This entails monitoring the peaks of a few tens of microlensing events with moderately high magnifications with 1-2m class telescopes. Planets of a few Earth masses are found to produce deviations of ∼5 per cent to the peaks of microlensing light curves with durations ∼(0.7-3) hr in events with magnification ∼100 if the projected separation of the planet lies in the annular region (0.85-1.2)rE. Similar deviations are produced by Earth mass planets in the annular region (0.95-1.05)rE. It is possible that sub-Earths could be detected very close to the Einstein ring if they are sufficiently abundant, and also planetary systems with more than one low-mass planet.