Gravitational Microlensing Events as a Target for SETI project
Detection of signals from a possible extrasolar technological civilization is one of the challenging efforts of science. In this work, we propose using natural telescopes made of single or binary gravitational lensing systems to magnify leakage of electromagnetic signals from a remote planet harbours an Extra Terrestrial Intelligent (ETI) technology. The gravitational microlensing surveys are monitoring a large area of Galactic bulge for searching microlensing events and each year they find more than 2000 events. These lenses are capable of playing the role of natural telescopes and in some occasions they can magnify signals from planets orbiting around the source stars in the gravitational microlensing systems. Assuming that frequency of electromagnetic waves used for telecommunication in ETIs is similar to ours, we propose follow-up observation of microlensing events with radio telescopes such as Square Kilometre Array (SKA), Low Frequency Demonstrators (LFD) and Mileura Wide-Field Array (MWA). Amplifying signals from leakage of broadcasting of Earth-like civilizations will allow us to detect them up to the center of Milky Way galaxy. Our analysis shows that in binary microlensing systems, the probability of amplification of signals from ETIs is more likely than that in the single microlensing events. Finally we propose a practical observational strategy with the follow-up observation of binary microlensing events with the SKA as a new program for searching ETIs. The probability of detection in the optimistic values for the factors of Drake equation is around one event per year.