Microlensing planet detection via geosynchronous and low Earth orbit satellites

Abstract

Planet detection through microlensing is usually limited by a well-known degeneracy in the Einstein timescale $t_E$, which prevents mass and distance of the lens to be univocally determined. It has been shown that a satellite in geosynchronous orbit could provide masses and distances for most standard planetary events ($t_E\approx 20$ days) via a microlens parallax measurement. This paper extends the analysis to shorter Einstein timescales, $t_E\approx 1$ day, when dealing with the case of Jupiter-mass lenses. We then study the capabilities of a low Earth orbit satellite on even shorter timescales, $t_E\approx 0.1$ days. A Fisher matrix analysis is employed to predict how the 1-$\sigma$ error on parallax depends on $t_E$ and the peak magnification of the microlensing event. It is shown that a geosynchronous satellite could detect parallaxes for Jupiter-mass free floaters and discover planetary systems around very low-mass brown dwarfs. Moreover, a low Earth orbit satellite could lead to the discovery of Earth-mass free-floating planets. Limitations to these results can be the strong requirements on the photometry, the effects of blending, and in the case of the low orbit, the Earth's umbra.

5 pages, 3 figures. Minor language edits. Accepted for publication in Astronomy & Astrophysics

References in corpus (3)

• Use and Abuse of the Fisher Information Matrix in the Assessment of Gravitational-Wave Parameter-Estimation Prospects
• A Sub-Earth-Mass Moon Orbiting a Gas Giant Primary or a High Velocity Planetary System in the Galactic Bulge
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Cited by in corpus (7)

• First simultaneous microlensing observations by two space telescopes: $Spitzer$ & $Swift$ reveal a brown dwarf in event OGLE-2015-BLG-1319
• WFIRST and EUCLID: enabling the microlensing parallax measurement from space
• Measuring microlensing parallax via simultaneous observations from Chinese Space Station Telescope and Roman Telescope
• OGLE-2015-BLG-1670Lb: A Cold Neptune beyond the Snow Line in the Provisional WFIRST Microlensing Survey Field
• Probability of simultaneous parallax detection for free-floating planet microlensing events near Galactic Centre
• Revealing Short-period Exoplanets and Brown Dwarfs in the Galactic Bulge using the Microlensing Xallarap Effect with the \textit{Nancy Grace Roman Space Telescope}
• Measuring the microlensing parallax from various space observatories