Measuring the Extragalactic Planet Occurrence Rate with TESS: Early Results from the Sagittarius Dwarf Galaxy Stream

While the Kepler survey discovered thousands of planets and allowed us to determine the occurrence rate of planets around solar type stars in the Milky Way thin disk, there is no statistical sample of extrasolar planets outside the Milky Way, which is key to assessing the role galactic environment may play in the planet formation process. While the Milky Way dwarf galaxy population is too distant to resolve into individual stars and too dim to obtain the precision necessary to identify transiting planets, the recent merger history of the Milky Way has provided a mechanism for bringing extragalactic populations to an accessible distance. Gaia DR3 results have identified large catalogs of high probability members of stellar streams within the Milky Way which originated in accreted dwarf galaxies. This provides us with a population of stars which are both extragalactic in nature, and at a distance and magnitude accessible to transit photometry in TESS. In this talk I will discuss our survey of tens of thousands of extragalactic stream stars, with a particular focus on the Sagittarius dwarf galaxy stream, and our search for transiting exoplanets around these targets using currently available TESS FFI data. I will demonstrate our current detection pipeline for these TESS mag ~17 target stars and how our injection-recovery tests show broad sensitivity to the classical hot-Jupiter population of planets. I will also discuss our current target list and candidates. Once completed, our survey will be the first statistical survey for exoplanets beyond the Milky Way, and provide a unique population of sources which all Milky Way transit surveys can be compared to.