Title: Determining the NIR Microlensing Event Rate at |b| <2 with the United Kingdom Infrared Telescope

Abstract: With the mid-2020s launch of the Wide Field Infrared Survey Telescope (WFIRST) fast approaching, it is becoming increasingly more important to understand the optimal spatial region for microlensing event detection. The Galactic center (i.e. where |b| < 2), which has the highest density of potential source stars in the Milky Way, has been historically understudied due to the obscuring properties of its high volume of gas and dust. The United Kingdom Infrared Survey Telescope (UKIRT) microlensing project has succeed in mitigating some of the reddening effect of Galactic dust by observing in the near-infrared over a long baseline from 2015-2019. Observations in the K and H NIR bands in unique fields have yielded hundreds of microlensing events detected via our UKIRT data reduction pipeline. Our goal has been combine our detections with image-level mock event injections in order to determine our survey’s detection efficiency. We then subsequently aim to derive the NIR microlensing event rate per square degree for the totality of our survey. Preliminary results suggest that sources with projected coordinates close to b = (0,0) exhibit a NIR microlensing event rate of ~75 x 10-6 events/year, with decreasing rates with increasing projected distance to the center. Understanding the intrinsic NIR microlensing event rate at low Galactic coordinates is crucial for informing mission design and field specifications for WFIRST.

Institution:  Vanderbilt University

Host:  Dan Stevens