Short-duration lensing events: II. Expectations and Protocols

TL;DR

This paper discusses the expectations and protocols for observing short-duration microlensing events, which are valuable for discovering low-mass objects, high-speed stars, and exoplanets.

Contribution

It provides a detailed analysis of expected event rates, parameter ranges, and introduces improved observation and modeling protocols for short-duration microlensing events.

Findings

Expected rates of short-duration events are computed.

Protocols for observing and modeling are developed.

Minor procedural improvements can enhance planet discovery.

Abstract

Ongoing microlensing observations by OGLE and MOA regularly identify and conduct high-cadence sampling of lensing events with Einstein diameter crossing time, tau_E, of 16 or fewer days. Events with estimated values of tau_E of one to two days have been detected. Short duration events tend to be generated by low-mass lenses or by lenses with high transverse velocities. We compute the expected rates, demonstrate the expected ranges of parameters for lenses of different mass, and develop a protocol for observing and modeling short-duration events. Relatively minor additions to the procedures presently used will increase the rate of planet discovery, and also discover or place limits on the population of high-speed dim stars and stellar remnants in the vicinity of the Sun.