The Roman Galactic Exoplanet Survey: Prospects for Constraining the Frequency of Earth-Analogs

Nov 24, 2020 - 11:00 am to 12:00 pm
Samson Johnson (Ohio State) via zoom

The frequency of Earth-like planets in the habitable zone of Sun-like stars (eta_Earth) is a fundamental input in estimating the occurrence rate of life resembling that on Earth, and therefore an important parameter for designing future direct imaging missions. eta_Earth is currently best estimated by the Kepler transit survey, but Earth-analog systems with long periods and shallow transits are on the edge of the survey's sensitivity. The Roman Galactic Exoplanet Survey will be able to detect Earth-analog systems through microlensing, but similarly they will be on the boundary of its sensitivity due to low-mass ratios and small projected separations. We perform simulations of the Roman Galactic Exoplanet Survey to estimate its sensitivity to these systems. Roman's ability to estimate eta_Earth will hinge on the extrapolation from systems with larger mass-ratios and wider projected separations. We predict that Roman will discover 1-3 Earth-analog systems with hosts likely near the Galactic center.