Rogue Worlds with Roman and Subaru/HSC
| Program ID | 19023 |
|---|---|
| Science Category | Exoplanets & Exoplanet Formation |
| Program Type | Analysis |
| Category | Medium |
| Principal Investigator | William DeRocco |
| PI Institution | University of Maryland, College Park |
| Co-Investigators |
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| Abstract | Free-floating planets (FFPs) are one of the most abundant, yet poorly understood demographics of exoplanets in the Galaxy. Though current observations suggest upwards of 20 FFPs with masses above that of Mars per star in the Galaxy (Sumi et al. 2023), this population has largely remained a mystery. Gravitational microlensing provides one of the only means of detecting these worlds, however existing efforts have been limited due to the challenges of ground-based observation. Roman's Galactic Bulge Time Domain Survey (GBTDS) is expected to detect hundreds to thousands of FFPs, providing our first opportunity to measure their abundance and mass distribution and test competing models of planet formation theory. However, Roman will be unable to measure FFP masses on its own. To measure an FFP's mass, simultaneous observations by two telescopes separated by a long baseline are required. The Earth-L2 baseline is ideal, however most ground-based telescopes are unable to match Roman's capabilities, hence are limited in their ability to jointly detect FFP events. One exception is the Hyper Suprime-Cam (HSC) on the Subaru Telescope. Recently, 20 nights of Subaru time were awarded for contemporaneous high-cadence monitoring of the Galactic bulge during the first three GBTDS seasons through the Roman-Subaru Synergistic Observations program. This proposal will leverage these observations to measure the masses of FFPs that Roman detects, providing a critical dataset for discriminating between competing FFP origin scenarios. |