SETI in the Spatio-Temporal Survey Domain (1907.04443v1)

Abstract: Traditional searches for extraterrestrial intelligence (SETI) or "technosignatures" focus on dedicated observations of single stars or regions in the sky to detect excess or transient emission from intelligent sources. The newest generation of synoptic time domain surveys enable an entirely new approach: spatio-temporal SETI, where technosignatures may be discovered from spatially resolved sources or multiple stars over time. Current optical time domain surveys such as ZTF and the Evryscope can probe 10-100 times more of the "Cosmic Haystack" parameter space volume than many radio SETI investigations. Small-aperture, high cadence surveys like Evryscope can be comparable in their Haystack volume completeness to deeper surveys including LSST. Investigations with these surveys can also be conducted at a fraction of the cost of dedicated SETI surveys, since they make use of data already being gathered. However, SETI methodology has not widely utilized such surveys, and the field is in need of new search algorithms that can account for signals in both the spatial and temporal domains. Here I describe the broad potential for modern wide-field time domain optical surveys to revolutionize our search for technosignatures, and illustrate some example SETI approaches using transiting exoplanets to form a distributed beacon.

• The paper demonstrates that integrating optical surveys expands the parameter space by 10-100 times compared to traditional radio methods.
• It introduces novel algorithms to identify technosignatures through coordinated signals and spatio-temporal variability patterns.
• The methodology leverages existing astrophysical survey data for cost-effective, reproducible SETI research and advanced signal detection.

SETI in the Spatio-Temporal Survey Domain

The search for extraterrestrial intelligence (SETI) has long suffered from the constraints imposed by traditional methodologies, which rely primarily on targeted observations using radio telescopes. In "SETI in the Spatio-Temporal Survey Domain," James R. A. Davenport presents a compelling argument for leveraging modern optical time-domain surveys as a novel avenue for detecting technosignatures. This paper explores the integration of optical surveys such as the Zwicky Transient Facility (ZTF) and Evryscope into the SETI framework, capitalizing on their ability to monitor vast portions of the sky with high temporal resolution.

Traditional Constraints and New Opportunities

SETI efforts have historically been hampered by the limited parameter space that can be explored at radio wavelengths, often compared to finding a needle in a cosmic haystack. The advent of large-scale synoptic surveys provides an opportunity to significantly expand this search space, testing for extraterrestrial signals using existing datasets. Davenport argues that optical surveys are particularly well-suited for this task, offering advantages in cost, spatial coverage, and temporal monitoring compared to radio SETI. By harnessing the wealth of data collected by surveys aimed at other astrophysical phenomena, SETI can be conducted in a more resource-efficient manner.

A New Approach: Survey SETI

The paper outlines the conceptual framework for "survey SETI," which involves searching for technosignatures across extensive datasets obtained from optical surveys. Davenport evaluates the potential for these surveys to cover larger volumes of the so-called "Cosmic Haystack," quantifying the parameter space they can probe. Current optical surveys have the capability of covering 10-100 times more parameter space than conventional radio missions, highlighting their potential to uncover unexplored phenomena.

Methodological Innovations and Example Strategies

Davenport emphasizes the need for new algorithms capable of handling spatio-temporal signals, proposing several novel strategies for technosignature detection. These include identifying unusual variability patterns, coordinated signals among multiple sources, and spatial over-densities in the distribution of light curve events. For example, the paper suggests using the distribution of transiting exoplanets as a potential signal, where clusters of similar transiting profiles or orbital configurations might indicate engineered structures.

To quantitatively compare optical surveys with radio approaches, the paper applies the "Cosmic Haystack" framework, initially developed for radio frequencies, to a selection of current and future optical surveys. This allows for a detailed assessment of the spatial and temporal completeness of different survey methodologies.

Implications and Future Directions

This paper highlights the transformative potential of integrating optical surveys into SETI research, suggesting that traditional assumptions about search strategies should be revisited. With the development of new statistical methods and machine learning algorithms, the search for technosignatures can now extend into dimensions previously considered impractical. Moreover, the reproducibility and openness of data from these optical surveys present a powerful tool in addressing the so-called "giggle factor" often associated with SETI research, which refers to the skepticism faced by SETI researchers due to the fringe nature of the field.

In conclusion, with appropriate algorithmic tools, optical time-domain surveys can facilitate a new era of technosignature detection, bridging the gap between radio and optical SETI and offering new insights into the search for extraterrestrial intelligence. As astronomy continues to evolve into an era of unprecedented data-driven discovery, approaches like those outlined by Davenport will be crucial in expanding the horizons of SETI research and possibly, the discovery of extraterrestrial life.