Microlensing optical depth and event rate in the OGLE-IV Galactic plane fields

Understand

Searches for gravitational microlensing events are traditionally concentrated on the central regions of the Galactic bulge but many microlensing events are expected to occur in the Galactic plane, far from the Galactic Center.

• Owing to the difficulty in conducting high-cadence observations of the Galactic plane over its vast area, which are necessary for the detection of microlensing events, their global properties were hitherto unknown.
• Here, we present results of the first comprehensive search for microlensing events in the Galactic plane.
• We searched an area of almost 3000 square degrees along the Galactic plane (|b|<7, 0<l<50, 190<l<360 deg) observed by the Optical Gravitational Lensing Experiment (OGLE) during 2013-2019 and detected 630 events.