Detection of Exoplanet as a Binary Source of Microlensing Events in WFIRST Survey

TL;DR

This study explores a novel method of exoplanet detection via microlensing in WFIRST data, focusing on planets orbiting source stars and using reflection or thermal emission, with low detection probabilities for rocky planets.

Contribution

It introduces a new detection channel for exoplanets in microlensing events, considering planets orbiting source stars and using their reflected or emitted light as signals.

Findings

Detection probability for rocky planets is virtually zero.

Detection probability for Jovian planets is around 0.012% in single lens events.

Detection rate in binary lens events is approximately 0.9%.

Abstract

We investigate the possibility of exoplanet detection orbiting source stars in microlensing events through WFIRST observations. We perform a Monto Carlo simulation on the detection rate of exoplanets via microlensing, assuming that each source star has at least one exoplanet. The exoplanet can reflect part of the light from the parent star or emit internal thermal radiation. In this new detection channel, we use microlensing as an amplifier to magnify the reflection light from the planet. In the literature, this mode of detecting exoplanets has been investigated much less than the usual mode in which the exoplanets are considered as one companion in binary lens events. Assuming $72$ days of observation per season with the cadence of $15$ minutes, we find the probability of rocky planet detection with this method to be virtually zero. However, there is non-zero probability, for the detection of Jovian planets. We estimate the detection rates of the exoplanets by this method, using WFIRST observation to be $0.012\%$ in single lens events and $0.9\%$ in the binary lens events.