60 Microlensing Events from the Three Years of Zwicky Transient Facility Phase One

Abstract

Microlensing events have historically been discovered throughout the Galactic bulge and plane by surveys designed solely for that purpose. We conduct the first multi-year search for microlensing events on the Zwicky Transient Facility (ZTF), an all-sky optical synoptic survey that observes the entire visible Northern sky every few nights. We discover 128 high quality microlensing events in the three years of ZTF-I using the bulk lightcurves in the ZTF Public Data Release 5. We find an excess of longduration Galactic plane events when comparing our results to both previous surveys and simulations. 35 of our events are found outside of the Galactic plane (|b| ≥ 15 • ), nearly tripling the number of previously discovered events in the stellar halo from surveys pointed toward the Magellanic Clouds and the Andromeda Galaxy. We also record 1690 ongoing candidate events as potential microlensing that can continue to be observed by ZTF-II for identification. The scalable and computationally efficient methods developed in this work can be applied to future synoptic surveys such as the Rubin Observatory's Legacy Survey of Space and Time and the Nancy Grace Roman Space Telescope as they attempt to find microlensing events in even larger and deeper datasets.

Gaia Data Release 3

“…The search among OGLE microlensing candidates from bulge and disc (Mróz et al 2019(Mróz et al , 2020b) also yielded no matches. We also checked the microlensing catalogue from ZTF, which started operating after 2018 (Rodriguez et al 2021;Medford et al 2022), and again found no matches to our events. We also extracted photometry from ZTF DR9 4 (Masci et al 2019) and visually inspected all light curves with ZTF data covering the years 2018-2022.…”

Gaia Data Release 3: Microlensing Events from All Over the Sky

“…The search among OGLE microlensing candidates from Bulge and Disk (Mróz et al 2019(Mróz et al , 2020b) also yielded zero matches. We also checked microlensing catalogue from ZTF, which started operating after 2018 (Rodriguez et al 2021;Medford et al 2022) and again found no matches to our events. We also extracted photometry from ZTF DR9 4 (Masci et al 2019) and visually inspected all light curves with ZTF data covering years 2018-2022.…”