Hunting cold planets: Breaking the Low Mass Planet Detection Limit with Euclid and Roman

The ESA EUCLID mission and NASA Nancy Grace Roman Space telescope mission have the potential to detect thousands of planets across a broad range of masses and semi-major axes. Both ROMAN and EUCLID will be located in halo orbits at the Earth-Sun L2 point, with a potential separation between them of up to 600.000 km, while observing the same sky frame. The ROMAN telescope will utilize the gravitational microlensing technique which is a unique tool for detecting and studying cold exoplanets of masses in the range Mars to Jupiter, orbiting any kind of star or stellar remnant all the way to the Galactic Bulge. Gravitational microlensing relies on the chance alignment of two or more stars in our galaxy. Over 100 planets have been found so far using this technique, and the Roman Telescope is expected to increase that by a factor of ten. One of the limiting factors of microlensing planet searches is to obtain accurate mass measurements. An approach to break this limit is to use constraints from high angular resolution follow-up observations (with KECK and HST until now) to measure source lens relative proper motions and flux ratios. Using simulated early EUCLID images of a star field containing 1691 microlensing events that ROMAN will observe, I will explain the complementarity of the two missions. I will show how two joint-surveys will better constrain the mass and distance of microlensing events, increase the detection of “free-floating” planets (FFPs) and lead to a breakthrough in our understanding of cold planet demographics and planetary formation theories.