Bayesian approach to SETI

Abstract

The search for technosignatures from hypothetical galactic civilizations is going through a new phase of intense activity. For the first time, a significant fraction of the vast search space is expected to be sampled in the foreseeable future, potentially bringing informative data about the abundance of detectable extraterrestrial civilizations, or the lack thereof. Starting from the current state of ignorance about the galactic population of non-natural electromagnetic signals, we formulate a Bayesian statistical model to infer the mean number of radio signals crossing Earth, assuming either non-detection or the detection of signals in future surveys of the Galaxy. Under fairly noninformative priors, we find that not detecting signals within about $1$ kly from Earth, while suggesting the lack of galactic emitters or at best the scarcity thereof, is nonetheless still consistent with a probability exceeding $10$ \% that typically over $\sim 100$ signals could be crossing Earth, with radiated power analogous to that of the Arecibo radar, but coming from farther in the Milky Way. The existence in the Galaxy of potentially detectable Arecibo-like emitters can be reasonably ruled out only if all-sky surveys detect no such signals up to a radius of about $40$ kly, an endeavor requiring detector sensitivities thousands times higher than those of current telescopes. Conversely, finding even one Arecibo-like signal within $\sim 1000$ light years, a possibility within reach of current detectors, implies almost certainly that typically more than $\sim 100$ signals of comparable radiated power cross the Earth, yet to be discovered.

Published in PNAS ahead of print October 1, 2018. Preprint has 13 pages, 7 figures + 7 pages of Supplementary Information with 5 figures

References in corpus (12)

• Bayes in the sky: Bayesian inference and model selection in cosmology
• The Five-Hundred-Meter Aperture Spherical Radio Telescope (FAST) Project
• The Breakthrough Listen Search for Intelligent Life: 1.1-1.9 GHz observations of 692 Nearby Stars
• The distribution of the ISM in the Milky Way A three-dimensional large-scale model
• The Breakthrough Listen Search for Intelligent Life: Target Selection of Nearby Stars and Galaxies
• A Search for Laser Emission with Megawatt Thresholds from 5600 FGKM Stars
• A VLA Search for Radio Signals from M31 and M33
• ALFABURST: A commensal search for Fast Radio Bursts with Arecibo
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• The SERENDIP III 70 cm Search for Extraterrestrial Intelligence

Cited by in corpus (11)

• The Breakthrough Listen Search for Intelligent Life: Observations of 1327 Nearby Stars over 1.10-3.45 GHz
• First SETI Observations with China's Five-hundred-meter Aperture Spherical radio Telescope (FAST)
• The Breakthrough Listen Search for Intelligent Life: MeerKAT Target Selection
• Simulation of the Earth's radio leakage from mobile towers as seen from selected nearby stellar systems
• Inferring the rate of technosignatures from 60 yr of nondetection
• Demography of galactic technosignatures
• Searching for Technosignatures: Implications of Detection and Non-Detection
• Technosignatures longevity and Lindy's law
• Limits of Detecting Extraterrestrial Civilizations
• Undetected past contacts with technological species: implications for technosignature science
• Commensal, Multi-user Observations with an Ethernet-based Jansky Very Large Array