Reconstructing The Free-floating Planet Mass Function With The Nancy Grace Roman Space Telescope

Free-floating planets comprise one of the most enigmatic populations of exoplanets in the Galaxy. Though ground-based observations point to a large abundance of these worlds, little is known about their origins and demographics.

In the coming years, the Nancy Grace Roman Space Telescope’s Galactic Bulge Time Domain Survey is expected to detect several hundred free-floating planets, providing the first opportunity to characterize these worlds at the population level.

We present a first study of Roman’s prospects for reconstructing the mass distribution of free-floating planets through population-level statistical inference. We find that depending on the true underlying mass distribution of free-floating planets in the Galaxy, Roman will be able to improve upon existing estimates of the abundance by orders of magnitudes in the largely unexplored mass range below that of Earth.

When applied to Roman’s observations, the methodology we present herein will be capable of discriminating between different hypothesized mass distributions at high statistical significance, opening a new window into the origins of these rogue worlds.

William DeRocco, Matthew T. Penny, Samson A. Johnson, Peter McGill

Comments: 20 pages, 14 figures, submitted to AJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2505.00092 [astro-ph.EP] (or arXiv:2505.00092v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2505.00092
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Submission history
From: William DeRocco
[v1] Wed, 30 Apr 2025 18:03:01 UTC (3,560 KB)
https://arxiv.org/abs/2505.00092
Astrobiology,