Exoplanet Detection by Spitzer via Microlensing Events

The Spitzer Space Telescope, NASA’s Great Observatory for infrared astronomy, was launched in 2003 and is performing extremely well, returning excellent scientific data from its Earth-trailing solar orbit. The exoplanets orbiting stars can reflect part of its light. In this work, we use microlensing as an amplifier to magnify the reflection signature from the planet.
In this work, we perform a Monto Carlo simulation on detection rate of exoplanets via microlensing, assuming that each source star has at least one exoplanet.
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 this kind of exoplanets by Spitzer to be 5.8 per year with a small impact parameter compared to the Einstein radius of the source star ($u_{min}\leq 0.1$) in single-lens microlensing events. This is a new channel of the exoplanet detection, corresponds to the high-magnification single-lens microlensing events. Moreover, we estimate the detection rates by assuming binary-lens microlensing events is 4.5.