Strategies for Maximizing Detection Rate in Radio SETI

Abstract

The Search for Extraterrestrial intelligence (SETI) is a scientific and cultural effort seeking evidence of intelligent life beyond earth. Radio SETI observes the radio spectrum for ''technosignatures" that could be produced by an advanced ET society. This work models radio SETI as an end-to-end system, and focuses on narrow-band intentional transmissions. We look at strategies to maximize the expected number of detections per year (DPY) of search. Assuming that ET civilizations will be associated with star systems, we want to maximize the number of stars that may be observed at one time. Assuming a representative star density, this requires maximizing the search volume in a cone defined by the detection range and field of view (FOV). The parameter trades are modified from the case where one simply maximizes signal-to-noise ratio. Instead, a joint optimization between FOV and sensitivity is needed. Some implications: 1) Instead of focusing on the terrestrial microwave window of 1-10 GHz, frequencies below 1 GHz may be optimal for detection rate due to the larger field of view; 2) Arrays of smaller dishes should be favored compared to a single dish of equivalent area; 3) Aperture arrays are desirable due to their large potential FOV. Many radio telescopes under development will provide both high sensitivity and large FOV, and should offer much improved SETI detection rates. Still higher DPY is needed, however, to achieve results in reasonable time horizons, which should be possible by greatly expanding computation capability to the next-generation wide-FOV antenna arrays.