Statistical Signatures of Panspermia in Exoplanet Surveys

Abstract

A fundamental astrobiological question is whether life can be transported between extrasolar systems. We propose a new strategy to answer this question based on the principle that life which arose via spreading will exhibit more clustering than life which arose spontaneously. We develop simple statistical models of panspermia to illustrate observable consequences of these excess correlations. Future searches for biosignatures in the atmospheres of exoplanets could test these predictions: a smoking gun signature of panspermia would be the detection of large regions in the Milky Way where life saturates its environment interspersed with voids where life is very uncommon. In a favorable scenario, detection of as few as $\sim 25$ biologically active exoplanets could yield a $5\sigma$ detection of panspermia. Detectability of position-space correlations is possible unless the timescale for life to become observable once seeded is longer than the timescale for stars to redistribute in the Milky Way.

5 pages, 2 figures, revised to include stellar migration, accepted to ApJL

References in corpus (7)

• The Transiting Exoplanet Survey Satellite
• The Transiting Exoplanet Survey Satellite: Simulations of planet detections and astrophysical false positives
• Vegetation's Red Edge: A Possible Spectroscopic Biosignature of Extraterrestrial Plants
• Detecting industrial pollution in the atmospheres of earth-like exoplanets
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Cited by in corpus (13)

• Enhanced interplanetary panspermia in the TRAPPIST-1 system
• Galactic Panspermia
• Relative Likelihood for Life as a Function of Cosmic Time
• Subsurface Exolife
• The Fermi Paradox and the Aurora Effect: Exo-civilization Settlement, Expansion and Steady States
• Habitable Evaporated Cores and the Occurrence of Panspermia near the Galactic Center
• Panspermia in a Milky Way-like Galaxy
• Eta-Earth Revisited II: Deriving a Maximum Number of Earth-like Habitats in the Galactic Disk
• Quantifying the information impact of future searches for exoplanetary biosignatures
• Dynamical and biological panspermia constraints within multi-planet exosystems
• Feasibility of Detecting Interstellar Panspermia in Astrophysical Environments
• On possible life-dispersal patterns beyond the Earth
• On the Habitability of Our Universe